Glossary

Welcome to your glossary of over 700 terms and definitions related to sectors with security, authentication, and trust at their core. The terms are arranged in alphabetical order and you can also filter them by individual sector: namely Authentication, Currency, Digital Currency, Holography, Identity, Tax Stamps, and Traceability. Looking for a specific word? Just type it in the Text Search box and you’ll be presented with all the entries in the glossary that contain this word.

While the emphasis of the glossary is on terms relating to security technologies and systems, it also extends to other terms commonly encountered in these different sectors. Is there a term missing that you need a definition for? Don’t hesitate to let us know at [email protected].

2D hologram – A holographic image style that places a two-dimensional plane of artwork at, in front of, or behind the image plane of the hologram.

2D/3D hologram – A holographic image style created by a series of two-dimensional planes of artwork that are layered into the image volume of the hologram.

3D printing
Also known as
Additive printing
– The construction of a three-dimensional object from a computer-aided design, whereby material is deposited, joined or solidified under computer control, with the material being added together, layer by layer.

Achromatic – An optical system free from dispersion or used to describe a colourless (grey tone monochrome) holographic image.

Acrylonitrile butadiene styrene – A common plastic material (along with PVC) used for the manufacture of moulded or injected card bodies for certain kinds of plastic cards.

Activation – A stage in the use of a tax stamp, when applicable taxes become due. Also refers to a unique identifier used for track and trace, which is activated at the point where the identifier is applied to an item and scanned, and then linked to that item in a central database.

Active security feature – An overt security feature identified by sight or touch alone. See also Passive security feature.

Additive colour – Colours created by the mixing of visible light emitted from different colour light sources.

Adhesive – A means of sticking two surfaces together. In the anticounterfeiting context label adhesive should allow effective application but prevent unauthorised removal.

Adulteration – The tampering of a product to extend its use by dilution or deliberate addition of a harmful substance that renders the product dangerous or less effective.

Aggregation – Allows the identification of individual items within an outer package to be recorded and associated with a unique identifier applied to that package. The identifier can then be used to record the movement of the outer package (together with the movement of its contents) throughout the distribution chain. In the case of cigarettes, this parent-child relationship can record the hierarchy between packs and cartons, cartons and master cases, and master cases and pallets.

Algorithm – A mathematical procedure or formula for solving a recurrent problem, based on conducting a sequence of specified actions. For example, an encryption algorithm transforms data according to specified actions to protect that data. Provides the basis for many proprietary coding systems.

Algorithmic stablecoin – A stablecoin that adjusts supply using algorithms to maintain price stability. An example of this is NuBits.

Alloy – A mixture of more than one metal.

Alphanumeric code – A human-readable character set containing both letters (A-Z) and numbers (0-9). The increased number of permutations resulting from using letters and numbers allows data to be encoded with fewer characters than if only numbers are used.

Analogue – Using a wristwatch as an example, an analogue watch uses the movement of hands over a dial to represent passing time. It’s not the same thing as time itself, but an analogy of time. Sometimes contrasted with ‘digital’, a numeric representation of information.

Anneal – A heat treatment to soften dies, planchettes or metal.

Anti-Stokes feature
Also known as
Upconversion
– A security feature that uses infrared radiation to create an emission within the visible spectrum. An anti-Stokes ink contains crystals of rare-earth metals (ytterbium thulium etc.) and glows when exposed to high-intensity IR light. Luminophores which glow green are the most commonly used.

Antibody detection – Authentication technology based on the affinity (binding) between small molecules (marker) added to the product or its packaging during production and a protein (the antibody) added during the verification test.

Anticopy feature – A security feature that does not accurately reproduce when copied or scanned using a mechanical or digital device. Includes printed security features integrated in the background of security printing which are invisible to the naked eye under normal inspection conditions but become visible or cause flaws to appear after copying or reproducing with a scanner.

Anticounterfeiting technology – Technical measures designed to prevent or detect counterfeiting and other forms of illicit trade. Not synonymous with non-secure track and trace technologies used for purely logistic purposes (codes on mail items for example).

Antimicrobial film – A topcoat layer added to the surface of any number of materials, including adhesive materials such as labels and tape. The film contains a bacteria-blocking agent called Agion, produced by combining silver ions and zeolite.

Antitampering feature – A feature such as a secure closure specifically used to resist the opening of a container or identify that a container has been opened.

Application (App) – Software on a mobile device used to link the holder to a specific web page/service.

Application programming interface (API) – A connection between computers or computer programmes. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build such a connection or interface is called an API specification. The term API may refer either to the specification or to the implementation.

Aqua-fugitive ink – Specially formulated ink which reacts when in contact with water-based reagents, leaving a visible mark.

Artificial intelligence (AI) – The theory and development of computer systems able to perform tasks that normally require human intelligence, such as visual perception, speech recognition, decision-making, and translation between languages.

Assay – A procedure that identifies the presence and amount of a substance (such as a marker or taggant) in a particular composition.

Asset-backed stablecoin – Stablecoins that are backed by assets such as money (ie. central bank reserves, banknotes or bank deposits), commodities (eg. gold), or other cryptocurrencies. Since stablecoins are not covered by deposit insurance and central banks do not act as lender of last resort for them, to have confidence in them they need to be fully backed. The type of asset and the legal rights of the holder are key to whether there is confidence in the stablecoin, although, ulltimately, simple confidence or belief is also a significant factor in whether they are stable or not. The profitability of the asset to the provider and their own funding model is a part of assessing the stablecoin.

Asymmetric cryptography – A process that uses a pair of related keys – one public and one private – to encrypt and decrypt a message and protect it from unauthorised use.

Atomic absorption spectroscopy (AAS) – An analytical technique used to determine how much of certain elements are in a sample. It uses the principle that atoms (and ions) can absorb light at a specific, unique wavelength. When this specific wavelength of light is provided, the energy (light) is absorbed by the atom.

Augmented reality (AR) – A technology that superimposes a computer-generated image onto a user’s actual view of the real world. AR devices often use the term ‘hologram’ to describe the heightened visual reality they provide.

Authentic – Something that is real, genuine, valid, of undisputed origin. Authentication is the process of confirming that a product, document or even person is authentic.

Authentication – The process of determining that a product, document or even person is authentic.

Automated teller machine (ATM)
Also known as
Cash dispenser
– Electronic device that primarily dispenses cash after identification of the customer, using a payment card or other device such as a mobile phone or biometric identification.

Automatic identification data capture (AIDC) – Digital technologies used to automatically capture data, including barcodes, smart cards, biometrics, RFID and NFC.

Average life – The time, on average, between the first issuance of a banknote and its withdrawal from circulation by the issuing central bank. High-value denominations usually have a longer average life than low-value ones which, due to their more frequent usage, deteriorate faster.

Aztec structure – A type of holographic recording that combines features of off-axis and volume recording schemes, with the result being a phase-quantised, or terraced surface relief pattern. The groove profile, instead of being sinusoidal, resembles a stepped pyramid.

Balance sheet relief mechanism – Arrangement according to which participants in the cash cycle (eg. banks or CITs) may hold cash inventories at defined locations in the name of the central bank or receive financial compensation from the central bank. This mechanism reduces the costs of inventories for participating commercial entities. See also Notes held to order (NHTO).

Banderol
Also known as
Banderole
– A band or tape used as a closure to seal or provide tamper resistance. A banderol(e) is another name for a tax stamp, usually referring to the long stamp placed over the neck of alcohol bottles.

Banding – Placing a paper strap around a set of banknotes (usually in bundles of 100, 200, or 250 notes of the same denomination), to hold them together.

Bank for International Settlements (BIS) – An international financial institution owned by central banks that ‘fosters international monetary and financial cooperation and serves as a bank for central banks’.

Banknote – A type of negotiable promissory note, issued by a bank or other licensed authority, payable to the bearer on demand. Often referred to as a bill in the US.

Barcode – A method of storing limited amounts of data in a linear array of lines and spaces (1D barcode) or larger amounts in a rectangular array (2D barcode).

Barcode – linear – A series of vertical printed black bars of controlled thickness and separation representing variable data information in a linear, one-dimensional format (eg. UPC, EAN).

Barcode – matrix – A 2D barcode (eg. datamatrix, QR code, dotcode), typically square-shaped, capable of representing more data per unit area than a linear barcode.

Beamsplitter – An optical device that divides a beam of light into two beams.

Bearer instrument – A type of fixed-income security in which no ownership information is recorded and the security is issued in physical form to the purchaser. The holder of a bearer instrument is presumed to be the owner, and whoever is in possession of the physical bond is entitled to the coupon payments.

Biaxially orientated polypropylene (BOPP) – A variant of polypropylene, a thermoplastic polymer that forms an ideal printing surface for labels and banknotes.

Bifluorescence – A component in a mixture (such as ink) that provides two distinctive emission spectra when excited by two different wavelengths.

Big dot little dot – A system used to produce void pantographs. Consists of two-dot patterns of differing sizes that allow a desired message or image to appear when an original document is copied. The system plays off the physical limitations of the optical systems in copiers and scanners. The little dots are sized below the optical resolution and thereby disappear when copied, while the larger dots are preserved and subsequently stand out visually.

Big Tech – Large, well-established technology companies that provide financial products and services, or products very similar to these, and that can include crypto products.

Billon – A low-grade alloy used for some minor coin issues, usually consisting of a mixture of silver and copper, and sometimes coated with a silver wash.

Bimetallic – Bimetallic coins consist of two metals or alloys that are bonded together, generally arranged with an outer ring around a contrasting centre. Trimetallic coins refer to coins with three rings made of three different metals or alloys.

Bimetallism – A monetary standard in which the value of the monetary unit is defined as equivalent to certain quantities of two metals, normally gold and silver, which are independently used as legal tender, but in a fixed exchange ratio to one another.

Biographical data – Attributes of a person or their life that are not biological or behavioural (biometric), and that cannot be measured. This includes information such as name, sex, age, nationality.

Biometric authentication – Authenticating a claim on identity by matching a captured biometric to a stored one.

Biometric characteristic – A biological (fingerprint, face, iris) or behavioural (gait, handwriting, signature, keystrokes) attribute of an individual that can be used for biometric recognition.

Biometric data – An attribute of the person held on a record that can be measured and against which the bearer of an ID document can be tested, such as fingerprint, face and iris.

Biometrics – The science and technology of measuring and statistically analysing biological data.

Birefringence – A phenomenon exhibited by certain materials in which an incident ray of light is split into two rays, called an ordinary ray and an extraordinary ray, which are plane-(linear) polarised in mutually orthogonal planes, or circular-polarised in opposite directions (left and right).

Bitcoin – Bitcoin is commonly referred to as a cryptocurrency, a digital means of exchange. It was developed by a set of anonymous authors under the pseudonym of Satoshi Nakamoto, and began operating in 2009 as a community project, without any relationship with or dependency on any government, state, company or body. The value of bitcoin is formed by a complicated system of mathematical algorithms and cryptography and it is not supported by any central bank or authority. Bitcoins are essentially accounting entries in a large database called a blockchain, which is unique but replicated in millions of computers connected to the internet. Bitcoins can be exchanged almost instantaneously for any currency and can be used for payment. The system has numerous pros and cons, and many central banks insist that bitcoin is not a currency but a highly speculative and high-risk asset. In reality it is reasonably quick and easy to buy cryptocurrencies but the exchanges make it harder and costlier to sell them.

Black box – The fraudulent act of connecting an unauthorised device to an automated teller machine in order to bypass security measures and gain access to cash. It is a type of cyber attack in which the attacker has little or no prior knowledge of the internal workings of the target system.

Blank
Also known as
Planchet
– A piece of coin-shaped metal that is stamped and made into a coin.

Blanket-to-blanket press – A printing method consisting of two blanket cylinders through which a sheet of paper is passed and printed on both sides.

Blazed grating – A diffraction grating which has a sawtooth profile structure.

Bleeding ink
Also known as
Penetrating ink
– Security ink containing dyes which, in combination with a solvent, penetrates the paper substrate so that any attempt at mechanical erasure will cause visible damage to the document.

Blind embossing
Also known as
Inkless, colourless or relief embossing
– A method of creating a raised design without the use of ink. Typically, two metal dies are used for this process: one with raised detail, and another with matching but recessed detail.

Blister pack – In the pharmaceutical context, a plastic or laminate tray with separate wells for each pill, sealed with blister foil.

Blockchain – A timestamped series of immutable records of data that are managed by a cluster of computers as a distributed ledger that is not owned by any single entity. The blocks of data are secured and bound to each other using cryptographic principles. A permissioned blockchain, defined in this glossary, can be owned by a single entity. For example, JPMcoin is owned by JPMorgan. There are now a wide range of examples of this type of blockchain.

Blockchain protocol – Rules that dictate how computers in a network verify new transactions and add them to the blockchain database.

Blow-fill-seal – An integrated process for forming plastic containers such as bottles and vials, filling them (often aseptically) and then sealing them without human intervention.

Bluetooth – A short-range wireless technology standard used for exchanging data between fixed and mobile devices over short distances and building personal area networks.

Body area network – A wireless network of wearable devices.

Book block – A type of a document construction in the form of a folded set of sheets or sections which are formed as a single/multiple booklet.

Book money – Primarily denotes bank account balances.

Bookend system – A term used to describe a pharmaceutical tracking approach with (usually) only two main points of control at the beginning and end of the supply chain (like bookends holding up books on a shelf). Developed as a pragmatic solution to implementing tracking in a complex multi-stakeholder distribution environment.

Bragg diffraction – The diffractive principle by which a layered stack of parallel reflecting surfaces of alternate higher and lower refractive index will reflect a beam of light, only when the reflected wavefronts are of an appropriate wavelength and orientation to produce constructive interference.

Bragg hologram – Any hologram in which the Bragg condition is preferential to the grating condition in forming the image. See also Volume hologram.

Braille text – Text readable by touch, consisting of raised dots. Often used on cardboard outer packs and mandatory in some jurisdictions.

Brand – A trademark or distinctive name that identifies a particular product or manufacturer.

Brand equity – The overall worth of a brand, including its tangible and intangible assets. Represents both the reputation and the value of a brand as a whole, as well as the sum of its individual parts.

Brand owner – The organisation that owns the specifications of a trade item, regardless of where and by whom it is manufactured.

Brand protection – The measures companies take to safeguard their brand against counterfeit products, unauthorised use of trademarks, and other forms of infringement.

Breeder document – Identificaton documents used as a foundation for creating other forms of personal verification. The most well-known breeder document is a birth certificate, but other breeder documents include marriage, and death certificates.

Brick – Ten straps of banknotes are commonly called a brick.

Bridge – The raised areas of paper between the windows of a security thread.

Briquette – A conglomerate of small chunks of shredded banknotes compressed or stuck together by the use of a binder. Banknotes not fit for circulation are destroyed in this way, and the compacting of the notes into briquettes facilitates the handling of this waste.

Broken banknote – Currency issued by a subsequently defunct bank. Also referred to as obsolete banknote.

Build-operate-transfer (BOT) – A project delivery method where a private entity receives a concession from the public sector to finance, design, construct, own, and operate a facility stated in the concession contract. This enables the project proponent to recover its investment, operating and maintenance expenses in the project. BOT is usually used in public–private partnerships.

Bullion – Physical gold, silver, or other precious metals of high purity, often kept in the form of bars, ingots, or coins. Bullion can sometimes be considered legal tender, and is often held as reserves by central banks or institutional investors. Bullion products are considered investment products and are traded at the daily price for the metal they contain.

Bundle – A set of normally five or 10 banknote straps of usually 100 notes each.

Burnishing – A form of surface preparation on proof or uncirculated coin blanks, using steel balls and detergent to remove any unwanted water marks from the surface of the blank.

Calender – The process of using hard pressure rollers to finish, glaze or smooth a sheet of material such as paper, textiles, or plastics.

Capacitive coupling
Also known as
Electrostatic coupling
– Refers to how energy moves between conductive elements separated by insulators. Capacitive touchscreens, found on smartphones, tablets and other mobile devices, are made up of multiple layers of glass and plastic, coated with a conductor material like indium tin oxide or conductive polymers. This conductive material responds when in contact with another electrical conductor, like a bare human finger.

Carton – A packaging unit of tobacco products. One carton usually contains 10 packs (or 200 individual cigarettes).

Cash – Traditional term used to describe money in physical form such as banknotes and coins. Starting to be used to describe value held in a digital format.

Cash centre – Processing centre for large volumes of cash, often in facilities with special security and logistic characteristics. Cash centres can be operated by a central bank or a commercial entity (usually a bank or cash-in-transit company).

Cash cycle – Represents the various stages of the cash lifecycle, from issuance by the central bank, circulation in the economy, to destruction by the central bank.

Cash in circulation – The value (or number of units) of banknotes and coins in circulation within an economy. Cash in circulation is included in the M1 monetary aggregate category (broad categories that measure the money supply in an economy) and comprises only banknotes and coins in circulation outside of the cash reserves held by monetary financial institutions. Cash in circulation also does not include the balance of the central bank’s own banknotes, as they have not been issued.

Cash recirculation – The action of putting back into circulation, over the counter or through an automated teller machine, banknotes and coins that cash handlers have received either from the public (as payment or as a deposit), or from another cash handler. The cash must be checked for authenticity and sorted for fitness by banks and cash-in-transit companies before being recirculated.

Cash recycling ATM – An ATM which can accept, validate and store banknotes which then become available for customers who wish to withdraw cash. Cash recycling ATMs need to comply with recirculation regulations imposed by the central bank. The term recycling is improperly used instead of recirculating but has become commonly accepted.

Cash-in-transit (CIT) – Describes the logistical handling of banknotes, coins, and items of value. This can include transportation, storage, counting and processing, and packaging. CIT companies are often responsible for the replenishment and servicing of ATMs and are often private security companies.

CashTech – The intersection of cash and digital technology, whereby software and apps are used to provide access to cash services for withdrawal, deposits and bill payments.

Cassette – A container used for storing banknotes when in transit or within ATMs and other cash devices. Smart versions act as sophisticated mobile vaults, with geolocation transmitters, remote electronic access keys, PIN pads and intelligent banknote destruction systems.

Casting – A method of hologram embossing in which a film of soft resin is applied to a nickel shim then exposed to ultraviolet light, causing the resin to harden by crosslinking. The resin film can then be removed and retains a faithful copy of the surface relief image that was present on the shim. This method of transferring an image from a nickel shim onto a plastic film, results in a bright image and causes very little wear to the shim.

Caustic surface – A surface that envelopes the light rays reflected or refracted by a curved mirror or interface.

CBDC – direct – CBDC accounts that are on the balance sheet of the central bank. The bank controls the ledger and is involved in the execution of retail payments.

Cellulose – A plant material that is used in the manufacture of pulp for papermaking.

Central bank
Also known as
Reserve bank/monetary authority
– An institution that manages the currency and operates the monetary policy of a state or formal monetary union. Central banks can also be tasked with supervising commercial banking systems. Central banks in most developed nations are institutionally independent from political interference.

Central bank digital currency (CBDC) – The virtual form of a fiat currency. A CBDC is an electronic record or digital token of a country’s official currency. As such, it is issued and regulated by the nation’s monetary authority or central bank, and is a direct liability of that bank.

Central bank digital currency – account-based – CBDCs held by the public at a central bank in individual bank accounts.

Central bank digital currency – hybrid or intermediate – CBDC accounts that are on the balance sheet of the central bank, with private intermediaries handling retail payments and, possibly, opening accounts. The difference between hybrid and intermediate CBDCs relates to whether the central bank keeps a central ledger of all transactions.

Central bank digital currency – retail or general purpose – CBDCs made available to the public. A general purpose CBDC can be used by the public or institutions.

Central bank digital currency – synthetic – A CBDC account that is not on the balance sheet of a central bank. Intermediaries hold the liability for the CBDC but are required to deposit 100% of the account at the central bank. Synthetic CBDs are not usually regarded as true CBDCs.

Central bank digital currency – token-based – The value of the CBDC is held as a token. The token can be stored in a number of places, such as in an account, wallet, or card. This term can be hard to define at a technical level and some central banks are trying to get away from terms such as token- and account-based because they are so imprecise. There is actually no good definition, but rather many definitions that are conflicting. For example, many now say the bitcoin is not really a token, as it is possible to clone the bitcoin system and have identities attached to all the addresses, but nothing would change in the code. So is that a token or an account?

Central bank digital currency – two-tiered – CBDCs that are first distributed to banks which then distribute them to individuals, much in the same way as cash. At each stage of the process, the CBDC is still a liability of the central bank. The core ledger is held by the central bank, but the private sector acts as payment service provider, delivering accounts and services to the public.

Central bank digital currency – wholesale – A CBDC issued and used for interbank settlements. It is not available to the public, only to financial institutions that are part of the central bank settlement system.

Central bank money – A liability of a central bank, including banknotes in circulation and deposits of other banks with the central bank.

Centralised ledger system – A ledger (ie. record of financial transactions), kept in one place. Often as part of a closed system, ie. with limited and controlled access, to help safeguard the ledger from unauthorised access. RTGS (real-time gross settlement) systems are, typically, centralised.

Changeover note – A run of banknotes with a change in signatures, series, or varieties without an interruption in the serial numbering. Occasionally, duplicate serial numbers can occur.

Check digit – Also known as a checksum character or control digit, this is usually the last digit of a number or barcode used to verify that the number is correct. A decoder calculates the checksum by performing a series of mathematical operations on the digits that precede the check digit, and comparing the result of the calculation to the value of the check digit.

Chemical reactive paper – Security papers which react to common solvents used to remove ink from a security document.

Chromium hologram – A hologram created with chromium-based foil for use in high security vehicle registration plates. Generally used in India.

Cipher – An encrypted message representing a range of characters

Circulation velocity – The length of time between a banknote being issued and being returned to a cash centre for sorting and a fitness assessment.

Civil registration – The recording, under law, of citizens’ vital events throughout their life, such as birth, death, marriage, divorce and adoption.

Classic hologram – A classic hologram is usually made using a 3D object, often a model. A laser beam is split in two and part of it is diverted onto the object, then reflected off it and allowed to combine (or interfere) with the other part of the beam known as the reference beam. The classic hologram is a recording of the interference pattern between the object and reference beams. A well-known example of a classic hologram is the dove used by Visa on its credit cards.

Clean note policy – A policy adopted by central banks to maintain the quality of circulating banknotes.

Clear window – A non-printed area of a substrate which is transparent when viewed against the light. In ID, a clear window is used for applying an additional image of the holder, as a verification filter or for visualising latent scrambled information.

Cliché printing – Transfer of ink by a pad or stamp directly onto packaging.

Closure seal – A means of sealing a pack to prevent accidental opening. For anticounterfeiting purposes closure seals need to be tamper evident and secure, or they can easily be replaced.

Cloud computing – On-demand access, via the internet, to computing resources – applications, physical servers, virtual servers, data storage, development tools, networking capabilities, and more – hosted at a remote data centre managed by a cloud services provider.

Coating – Typically an integral layer of material added to alter, enhance or protect the surface properties of an underlying base substrate or printed surface.

Coaxial light – Light that passes through an optical system parallel to the optical axis, for instance where the direction of illumination and direction of observation are in parallel. Coaxial light is used to reveal hidden motifs in retroreflective laminate.

Code – A system of words, letters, figures, or symbols used to represent certain information.

Coercivity – The magnetic field strength necessary to demagnetise a ferromagnetic material that is magnetised to saturation.

Coherence – The degree to which photons in a beam of light are in phase.

Coils – Long strips of metal from which coin blanks are punched.

Coin – Usually a small, flat, round piece of metal alloy (or combination of metals), marked with a device and used primarily as legal tender. Issued by government authorities, coins are standardised in weight and composition and are produced at mints.

Coin-reactive ink – An ink that changes colour when scraped with a coin or similar metallic object.

Cold foiling – A foil application process that does not require heat.

Collation mark
Also known as
Floating numeration
– Originally a bookbinding term. In order to produce a complete book, the various parts must be collated in the right order. This is ensured by placing collation marks as check marks (in the case of books, usually at the spine of the book block) in a staggered arrangement from top to bottom. In passports, this type of register mark or position mark is an additional safeguard. It makes it easier to spot whether any pages have been exchanged or removed. It can be invisible under normal light, as a fluorescent overprint, or a visible feature (using normal or fluorescent ink). The combination of collation mark and page numbers is sometimes called floating numeration.

Colorietary – The analysis and measurement of colour. Often used as a relatively cheap field-based technique.

Colour shift – An optically variable effect whereby a material – usually a thin film or ink – changes from one colour to another, or from one colour to clear, when the viewing angle is altered.

Commemorative banknote – A banknote issued by a central bank to mark a special occasion or in remembrance of a person. These banknotes tend to have special features in terms of design, structure and composition. Their production may be limited in number of prints. Not all countries issue commemorative banknotes. The banknote may, or may not, be legal tender.

Commercial bank – A financial institution which accepts deposits from the public and gives loans for the purposes of consumption and investment to make profit. It can also refer to a bank, or a division of a large bank, which deals with corporations or large/middle-sized business to differentiate it from a retail bank and investment bank. Commercial banks include private and public sector banks.

Competent authority – A government agency designated to implement a system, such as a tax stamp and track and trace solution.

Complementary metal oxide semiconductor – The semiconductor technology used in most of today’s integrated circuits.

Composite – In the context of substrates, this is used to describe paper/polymer combinations – either when the polymer forms the core, with the paper fused to the polymer, or when the paper forms the core, with polymer layers laminated either side. Composite substrates combine the security properties of paper (including the integration of threads and watermarks) with the durability of polymer.

Computer-generated hologram – A technique that uses computational methods to calculate the interference pattern that would have been created by a reference beam interfering with an object beam. The pattern is printed onto a mask or film to be viewed using illumination from a suitable light source.

Concatenation – The representation of several element strings in one barcode.

Consensus – Consensus is required for updates or transactions on blockchains. It refers to the need to validate new data before writing updates of information to the blockchain. Similar to the term ‘blockchain’, there are different types of consensus mechanisms. Early crypto consensus required agreement by the majority of relevant actors on the blockchain as to the status of the ledger, whereas more recent versions of blockchain use distributed consensus mechanisms, relying on a fewer number of nodes required for establishing consensus.

Continuous inkjet – A digital printing technique in which a continuous fine stream of electricity charged ink is formed and diverted onto the substrate as needed to form the printed image. Unused ink is collected and reused.

Converter – A packaging supplier who converts raw materials (paper, carton, board, aluminium foil etc.) into finished packaging components. The term is often used as a loose synonym for a packaging printer and the two functions are often combined into the same supplier.

Convertibility system – A legal system that previously operated under the gold standard, allowing the conversion of banknotes into gold coins, gold bars or gold-denominated certificates payable in gold on demand, according to established conversion rates.

Counterfeit – The illegal production and sale of goods (including packaging) bearing a trademark that is identical to a validly registered trademark or that cannot be distinguished from such a trademark. Also refers to the reproduction of a banknote or security document that looks authentic but has been manufactured fraudulently with the intent to deceive the public.

Counterfeit monitoring system (CMS) – A central database in the Eurosystem area, containing all technical and statistical information on counterfeiting, both on euro banknotes and coins, whether originated in EU member states or third countries.

Covert laser readable image – An image, symbol or text that is invisible to the unaided eye as well as under a microscope, but that can be visualised by a laser beam. It is formed when recording a hologram image using e-beam lithography, as a 1 micron-sized area on the hologram surface.

Covert security feature
Also known as
Level 3 security
– Covert (or hidden) features require a detector or instrument in their detection, which are usually only available to officials such as enforcement authorities and central banks.The general public and supply chain operators generally do not know about these features.

Credential – The means by which the identity of a person is authenticated in a trust framework. The credential may be physical (a document), digital (a password) or virtual (a string of digits).

Crypto exchange – A place where cryptocurrencies are bought and sold.

Crypto-backed token – A subset of asset-referenced tokens which reference their value in relation to other cryptoassets.

Cryptoasset – A digital representation of value or contractual rights, using some form of distributed ledger technology, which can be transferred, stored or traded electronically using cryptography. Cryptoassets are said to be decentralised since the issuance and transfer of the currency is not controlled by any central bank or other actor. Examples of cryptoassets include NFTs and cryptocurrencies.

Cryptoasset service provider (CASP) – Any person whose occupation or business is the provision of one or more cryptoasset services to third parties on a professional basis. Cryptoasset services include the provision of an exchange, including automated processes, enabling the exchange of cryptoassets for money, or of one cryptoasset for another cryptoasset. A CASP also offers custodian services, eg. through the provision of a custodial wallet to hold the cryptocurrencies.

Cryptocurrency – A number generated by an algorithm which is then recorded in a distributed ledger linked to a digital key held by the owner. Cryptocurrencies are not issued by a government and are not backed by assets. Their value lies in their scarcity, with a limit on the quantity created.

Cryptography – A method of protecting information and communications through the use of codes.

Currency – The official means of payment of a state/monetary union recognised as such by monetary laws.

Custom barcode – The use of a non-standard system of bars and spaces to encode data.

Cybercrime – Crime committed to steal or defraud people of electronic money, or crypto-assets, online.

Cybersecurity – Protecting data and communications against attacks from (amongst other things) malware, denial of service and phishing attacks.

Cylinder mould machine – A papermaking machine that drains stock through a fine wire mesh cylinder rotating inside a vat of pulp stock, to form a continuous wet ply of board. This method is not customarily used for documents like tax stamps, due to the weight of the paper, and is rather used for banknote paper production. Tax stamp paper is instead produced by a Fourdrinier machine.

Dandy roll – A mesh-covered hollow roll placed on top of a Fourdrinier papermaking machine. The dandy roll breaks up fibre clumps to improve sheet formation and can also create watermarks in paper, by pressing onto newly formed fibres. If the roll has been produced with raised elements, those elements press into the fibres leaving an impression which, when the paper is formed, allows more light to be seen relative to the thicker background paper. This is a form of watermark, albeit only 2D.

Data carrier – In the context of track and trace, usually refers to a barcode (primarily 2D), or a microchip carrying track and trace data in a machine-readable format.

Data page – The information page in a passport containing photo and personal details such as name, date of birth, nationality and sex.

Data repository – A database used to store track and trace data, for example.

Datamatrix code – A 2D code consisting of black and white cells or dots arranged in a square or rectangular pattern, also known as a matrix. The information to be encoded can be text or numeric data. Usual data size is from a few bytes up to 1556 bytes.

Date – The year in which a medal or coin was minted. On a banknote, the date is usually the year in which the issuance of that banknote – not its printing or entering into circulation – was formally authorised.

Daylight fluorescent ink – Fluorescent ink that is activated by visible light, instead of the more customary UV radiation.

Debossing – Creating an image or text (such as expiry and batch data) which is sunk below the level of the surrounding substrate using a die plate or punch.

Decal – An image or print that can be moved from one surface onto another, usually with the aid of heat or water.

Decentralised finance (DeFi) – An umbrella term for the provision of financial applications that is achieved directly between two parties without the need for financial intermediaries, and that often uses technology based on distributed ledgers and ‘smart contracts’.

Decentralised ledger system – A ledger system, recording transactions and holdings, which is held in multiple places and simultaneously updated. See Distributed ledger technology for a description of the technical infrastructure on which distributed ledger systems can be based.

Decimalisation – The conversion of a system of currency to units related by powers of 10.

Decoding – The translation of a code into a format that is more generally understood.

Decryption – The process of converting encrypted data back to its original form, often with the use of a covert key or password.

Deep fake – Synthetic media that have been digitally manipulated to replace one person’s likeness with that of another. Can also refer to computer-generated images of human subjects that do not exist in real life.

Demetallisation – A two-stage process in which metal, usually aluminium, is deposited onto a hologram or OVD and then selectively removed in order to create a design. The removal is achieved by either first printing a protective resin onto the metallic layer then dissolving away the unprotected metal, or ablating the metal with a laser beam. Used for security threads and foils in banknotes.

Demonetisation – The act of stripping a currency unit of its status as legal tender. This occurs whenever there is a change of national currency. Sometimes, a country completely replaces the old currency with new currency.

Denomination – The stated face value of a banknote or coin.

Dichromated gelatin – A chemical-gelatin mix that produces very bright images in a golden-yellow colour. The images have limited depth but can be viewed in extended light sources of poor quality. See also Volume hologram.

Die – A hardened metal tool, the face of which carries an engraved design for cutting or shaping low-strength materials, such as fibre, foil, paper, plastics, pressure-sensitive labels and sheet metal. Dies are used to create coins from metal blanks.

Diem – A permissioned blockchain-based payment system proposed by the American social media company Facebook, Inc. The plan also includes a private currency implemented as a cryptocurrency. Originally called Libra.

Diffraction – The phenomenon whereby lightwaves are bent as a result of passing through small apertures or around small objects or lines whose dimensions are comparable to the light wavelength. Of particular interest are gratings (a pattern of such lines) because these have the ability to bend light of different wavelengths by different amounts. Hence, they produce a prismatic effect of splitting white light into the colours of the rainbow – a feature typical to most DOVIDs.

Diffractive optically variable image device (DOVID) – A collective term for images that display complex visual effects that change according to the viewing angle, based on the phenomenon of diffraction. These effects are varied and typically three-dimensional, kinetic (exhibiting movement), multichannel (where one image, or part of an image, changes into another) or animated (ie. stereograms). DOVIDs include holograms, Kinegrams and other diffractive features.

Digifeiting – The reproduction (as in counterfeiting) of documents and packaging using digital reprographic technology.

Digital – The storage, transmission, manipulation and reproduction of data, images, sounds, etc., by a process that uses groups of electronic bits represented as 1 or 0.

Digital asset – Anything that exists in binary data which is self-contained, uniquely identifiable, and has a value or right to use. Data that do not possess that right are not considered assets.

Digital currency electronic payment (DCEP) – Name of China’s CBDC. See also e-yuan/e-CNY.

Digital dollar – Informal term for a US central bank digital currency.

Digital driving licence (mDL) – A mobile app that replaces a physical driving licence. Also known as mDL (mobile driving licence).

Digital euro – Informal term for a European central bank digital currency.

Digital identification system – An identification system that includes data capture, validation, storage and transfer, credential management, and identity verification and authentication.

Digital identity – The composite of electronically captured and stored attributes and credentials that uniquely identify a person.

Digital printing – Any printing technology capable of producing printed materials directly from a computer file. Digital printing does not require an intermediary medium such as film, nor an intermediary machine such as a platemaker. Non-impact printing such as laser, inkjet and dye sublimation all fall into this category.

Digital Product Passport (DPP) – The European Commission defines a ‘product passport’ as a product-specific dataset that can be electronically accessed via a data carrier to facilitate the electronic registration, processing, and sharing of product-related information among supply chain entities, authorities, and consumers.

Digital signature – A type of electronic signature that protects a document or authenticates a device by encryption with digital codes that are difficult to duplicate or decrypt.

Digital tax stamp – Commonly refers to a tax stamp which carries a digitally generated and printed unique identifier.

Digital twin – A virtual replica of a physical object, person, or process that can be used to simulate the object’s behaviour and optimise its performance.

Digital wallet – Can be in the form of an app, card or universal access device. It refers to a place where electronic money is held in token form.

Direct laser writer – An origination method that uses a single laser beam to create high-resolution structures on a photoresist.

Direct marking – A method of applying codes or information directly onto a product, without the use of a tax stamp or other label.

Disintermediation – A reduction in the use of intermediaries in order to connect participants in a transaction directly. In terms of central bank digital currencies (CBDCs), if the public is able to have an account and hold CBDC funds at a central bank, then there is less or even no need for it to hold private money in a commercial bank account. The services of the commercial bank account have therefore been disintermediated.

Dissolution test – The process of dissolving a solid dosage form in a solvent (usually water) and measuring genuine drugs and unsophisticated copies.

Distributed ledger technology (DLT) – Technological infrastructure and protocols that allow simultaneous access, validation, and record updating in an immutable manner across a network spread over multiple entities or locations, with no central hub. Generally associated with blockchain systems.

Diversion – The unauthorised transfer of goods from one jurisdiction to another in order to bypass taxation or regulatory requirements.

DNA taggant – Organic molecular particles based on DNA carbon compounds, either naturally occurring or synthetic. Typically used to tag documents or products for subsequent testing to prove authenticity.

Dollarisation – The process by which the US dollar is de facto adopted as the currency of a country. Dollarisation can be unofficial (the public chooses to hold dollars), or official (the central bank and government do not produce their own banknotes, eg. Ecuador).

Dot matrix hologram – A surface relief hologram built up from an array of tiny diffractive gratings arranged at certain angles. The ‘dots’ are a point at which two microscopic beams of laser light meet at an angle and produce an interference pattern. In a dot matrix machine, a mechanical arrangement moves this point of light in a matrix pattern relative to a photosensitive plate. According to the final image required, the angle at which each dot is exposed into the matrix is determined by mathematical calculation. It is thus possible to construct fully synthetic images of objects that never existed in real life.

Dot matrix printer – An impact printer that uses a fixed number of pins or wires, typically arranged in one or several vertical columns. The pins strike an ink-coated ribbon and force contact between the ribbon and the paper, so that each pin makes a small dot on the paper. The combination of these dots forms a dot matrix image allowing for various types of characters and digits to be reproduced. While inkjet and laser printers technically exhibit dot matrix printing, they are not considered to be ‘dot matrix printers’. Dot matrix printers are often used for counterfeiting the serial numbers on banknotes.

Dots per inch (DPI) – Used to measure the resolution of an image both on screen and in print. DPI measures how many dots fit into a linear inch, therefore the higher the DPI, the more detail can be shown in an image.

Double spending – A potential risk in a digital cash scheme in which the same single digital token can be spent more than once. Unlike physical cash, a digital token consists of a digital file that can be duplicated or falsified.

Down-conversion – An ink or substance which absorbs incident light at a specific wavelength and emits it at a lower energy (longer wavelength). Usually these substrates absorb ultraviolet light and emit visible light. See also Upconversion.

Drop-on-demand inkjet – A digital printing technology used on production lines often to print variable data such as lot numbers and expiry dates. In contrast to continuous inkjet, DOD printers only create ink drops as needed to form the image. They tend to be faster than continuous inkjet printers.

Dummy banknote
Also known as
Test note
– A banknote that is not legal tender and printed during the testing of a new family of banknotes. It is subject to special security measures even though it is designed not to be confused with a legitimate banknote. A dummy banknote can also be produced for special training purposes eg. for blind and partially sighted people.

e-yuan
Also known as
e-CNY
– Unit of exchange used in China’s DCEP system.

ECC 200 – The newest version of the datamatrix code, the most commonly used GS1-compliant 2D matrix code in pharmaceuticals.

Economic operator – Under the EU Tobacco Products Directive this refers to any natural or legal person involved in the trade of tobacco products, including for export, from the manufacturer to the last economic operator before the first retail outlet.

Edge cut – When two layers each with unique shapes, are partially revealed on the front and back of a data page.

Efficiency – In holography, this refers to the brightness of an image. It is the ratio of diffracted to incident light intensity.

Effigy – A sculpted image of a person, usually a monarch, that appears on the obverse of a coin or banknote.

eGate – Also known as electronic gates, eGates are automated passport control systems that use biometric technology to authenticate the identity of passengers. These gates scan the passport and take a photo of the passenger’s face, which is then compared to the digital image stored in the passport’s microchip.

Electroforming – The process of converting a holographic image from photoresist or plastic to metal (nickel). See also Shim.

Electromagnetic spectrum – The complete group of waves that range in frequency from radio waves to gamma rays, but all travel at the speed of light.

Electron beam lithography (E-beam) – The technique of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist. The whole origination process is undertaken in a vacuum chamber where the e-beam writes onto the resist plate. This is sometimes referred to as a direct write process. It is used to create holographic images.

Electronic identification and trust services regulation (eIDAS) – An EU regulation on electronic identification and trust services for electronic transactions in the European Single Market, established under EU Regulation 910/2014 of 23 July 2014.

Electronic Product Code (EPC ) – A data standard for the unique identification of any individual item around the world. Whereas a Global Trade Item Number (GTIN) identifies a class of trade item, such as ‘two-litre Acme bottled water’, an EPC can only identify one particular two-litre bottle of Acme water. Only the combination of a GTIN plus a serial number corresponds to an EPC.

Electronic Product Code Information Service (EPCIS) – A global GS1 product code standard for creating and sharing visibility event data, both within and across enterprises, to give users a shared view of physical or digital objects within a relevant business context.

Electronic signature – An electronic authentication technique that is a legal substitute for a handwritten signature.

Electroplating
Also known as
Electrochemical deposition
– A process for producing a metal coating of copper, nickel or bronze on a core steel or alloy substrate through the reduction of cations (positively charged ions) of that metal by means of a direct electric current. Electroplating is an alternative method of producing less expensive coin blanks while maintaining the visual and technical characteristics of a solid alloy-based coin. Circulating coins in traditional alloys do not undergo the electroplating process.

Embedded feature – Security features embedded in the paper during the production process or inserted between laminated layers. These include threads, planchettes, microtaggants, microcapsules and other devices, which cannot be removed or added retroactively without destroying the paper.

Embossing – The transfer of a raised pattern from a hard plate to a softer material. This mechanical transfer (which can be made through a seal, stamp or die) is usually facilitated by means of heat and always with pressure.

Encoding – The conversion of information or data into a code.

Encryption – The conversion of data or information into a format that requires a key or password to access the data.

Endless text – Repeated, sometimes unspaced lines of text in the background or security thread of a secure document.

Energy-dispersive X-ray spectroscopy (EDX (or EDS)) – An X-ray technique for identifying the elemental composition of materials.

Environmental, social and governance (ESG) – A framework used to assess an organisation’s business practices and performance on various sustainability and ethical issues.

ePassport
Also known as
Biometric passport
– A document in the form of a book or a card with an electronic microchip and antenna. The chip contains the holder’s scrambled personal data: eg. digital photo, name, data from the machine-readable zone, fingerprints, iris. The data is read by special devices and compared to personalisation data on the document, the holder’s physical data and the database.

EPCglobal – A GS1 subsidiary organisation administering Electronic Product Code systems and coordinating the development of associated data standards.

ePedigree – An electronic statement of a product’s history and passage through the supply chain, with each movement and transaction recorded so that, at any point in the chain and at its end, the lineage of the product can be obtained. Especially used to record batches of pharmaceutical products.

Erasable ink – Ink that rubs off when an attempt is made to erase information in the area that has been printed. The ink will also affect the paper in the same manner as solvent/chemical reactive inks, providing two security features in one. Often used to print the background of a cheque.

Ether – The name of a popular cryptocurrency operating on the Ethereum network.

EU Tobacco Products Directive (TPD) – The Tobacco Products Directive (2014/40/EU) is a directive of the European Union which places limits on the sale and merchandising of tobacco and related products in the EU. The TPD aims to improve the functioning of the internal market for tobacco and related products, while ensuring a high level of health protection for European citizens. Under the TPD, all member states were required to implement unit-level track and trace and security features by May 2019.

Euroisation – The process by which the euro is de facto adopted as the currency of a country.

European Article Number-13 barcode (EAN-13) – A 1D (linear) barcode developed as a superset of the UPC code, with an additional digit allowing a tenfold increase in the number of possible unique values. Like UPC codes, EANs encode global trade item numbers (GTINs) in line with GS1 international standards.

European Article Number-8 barcode (EAN-8) – A 1D (linear) barcode of the EAN/UPC symbology, used to label small consumer products with limited space for a barcode.

European Currency Unit (ECU) – A unit of account used by the European Economic Community composed of a basket of member country currencies. The value of the ECU was calculated as a weighted average of the value of the currencies comprising the basket. On 1 January 1999, the euro replaced the ECU at parity.

Europol – A body created within the European Union to support EU member states in the fight against terrorism, cybercrime and other serious and organised forms of crime, like currency counterfeiting.

eVisa – Also called electronic or online visa. It is simply a visa that can be applied for online but is no different to other types of travel visas.

Exchange – cryptocurrency – Websites where people buy, trade and hold cryptocurrencies.

Exchange – damaged banknote – Central banks exchange legal tender banknotes that are mutilated or damaged, when a certain percentage (usually more than 50% of the banknote) is presented or, when 50% or less is presented, and the remainder is shown to be destroyed.

Excise tax
Also known as
Sin tax
– Taxation imposed by countries as a levy for specific items such as tobacco or alcohol. Also called sin tax due to its association with so-called ‘sinful’ products.

Expression of interest (EOI) – Part of the qualification process to receive a tender document. The buyer (eg. a government organisation) is requesting a provider to express an interest in providing goods and services for a project.

Eye mark
Also known as
Registration mark
– A black rectangle printed on the edge of labels and other printed materials, which is read by a machine to locate where one label starts and the next ends.

Face value – The figure or amount written on a banknote or coin indicating the amount of its economic value. Usually written in letters and numbers.

False and Authentic Documents Online (FADO) – An EU-accredited system for exchanging classified information on false as well as genuine travel and identity documents between document experts. Intranet FADO (iFADO) is the access-restricted, second level of FADO, for governmental and law enforcement use.

Family
Also known as
Series
– Banknotes form a family when a series of banknotes are designed and issued as part of a coherent set of notes. They maintain traits that identify them as members of the same group (unity of design, uniformity of structure, etc.), while they may be of different size.

Farm-to-fork traceability – A term used in food traceability for describing end-to-end track and trace of food products, from the field where they were grown to the consumers who purchased them.

Fast Identity Online Alliance (FIDO) – An open industry association for developing and promoting authentication standards that help reduce over-reliance on passwords. The alliance supports authentication technologies, including biometrics such as fingerprint and iris scanners, and voice and facial recognition.

Fiat currency – A currency established as money, often by government regulation, without an intrinsic value, unlike a precious metal or a piece of merchandise. A development step from the use of commodity money, whose value comes from the commodity from which it is made (such as gold, silk, cigarettes).

Fiduciary circulation – Expression used by economists and monetary specialists to refer to the amount of money in circulation.

Fifth generation wireless network (5G) – A new global wireless standard after 1G, 2G, 3G, and 4G networks. 5G works at higher frequencies than its predecessors, resulting in greater bandwidth and faster data transfer. 5G therefore enables a new kind of network designed to connect virtually everyone and everything together, including machines, objects, and devices.

Financial inclusion – A process by which individuals and businesses can access appropriate, affordable, and timely financial products and services. While it is recognised that not all individuals need or want financial services, the goal of financial inclusion is to remove all barriers, both on the supply side and demand side. Supply side barriers stem from financial institutions themselves. They often indicate poor financial infrastructure, and include lack of nearby financial institutions, high costs to opening accounts, or documentation requirements. Demand side barriers refer to aspects of the individual seeking financial services and include lack of proof of identity, financial illiteracy, lack of financial capability, or cultural or religious beliefs that impact their financial decisions.There is growing scepticism from some experts about the effectiveness of financial inclusion as an economic and social development tool.

Fingerprinting – document
Also known as
Document biometrics/ physical unclonable function
– Refers to the combination of scanning and software programmes with unique physical characteristics intrinsic to a product or secure document. Fingerprinting is based on the fundamental premise that at the microscopic or molecular level the characteristics of every printed document or package are unique to that item.

FinTech – An umbrella term describing technology-enabled innovation in financial services, regardless of the nature or size of the entity providing the services, which could result in new business models, applications, processes and products.

Fiscus – State treasury.

Fit – A used banknote, which has not suffered any cuts, scrapes, tears, punctures, or marks and which presents a degree of soiling or wear considered acceptable by the central bank to be returned into circulation.

Flexographic printing
Also known as
Flexography
– A rotary relief printing method whereby a mirrored 3D relief of the required image is created in a rubber or polymer material. A measured amount of ink is deposited upon the surface of the printing plate, which then rotates, making contact with the substrate and transferring the ink.

Floating image – An optically variable element visually perceived as an image hovering or floating in space above or below a document’s surface.

Fluorescence – A type of luminescence, describing the ability of some molecules or materials to absorb ultraviolet (UV) energy and immediately re-emit this energy within the visible spectrum, as a glowing light. The emitted light disappears as soon as the excitation light is extinguished. There is no persistence of emitted light as in the case of phosphorescence.

Fluorescent fibre – UV-activated fibres that are randomly distributed across the surface and through the volume of security paper during the papermaking process.

Fluorescent hi-lite – Small coloured or colourless particles of a different size randomly embedded in paper pulp during the manufacturing process. The particles glow when exposed to UV light.

Fluorescent ink – UV-activated ink that ceases to glow immediately after the illuminating light source has been turned off.

Fluorescent planchette – Small, coloured discs with fluorescent properties usually mixed into the paper pulp during the papermaking process.

Foil – A material comprising a polyester carrier with one or more coatings, a release layer and an adhesive layer. The foil is transferred – generally by heat – onto paper, and the carrier is stripped away, leaving the coating bonded to the substrate by the adhesive. This coating can be plain or imaged, monochrome or coloured, colour-shifting, iridescent, metallised, holographic, etc. Also known as hot stamping or transfer foil. Foils are generally applied to banknotes as a continuous stripe (typically measuring 6-10mm wide) or a patch (typically square, circular or elliptical).

Forensic security feature
Also known as
Level 4 security feature
– Security feature reserved for special departments or officials. Special tools or laboratories are required to reveal their presence and characteristics. The presence and nature of these features are generally kept a closely guarded secret and they are typically used after an enforcement raid to provide definitive proof of the authenticity of a product or document. Such proof can be used, if necessary, as evidence in a court of law.

Fork – Where a second version of a database is created.

Form factor – A hardware design aspect that defines and prescribes the size, shape, and other physical specifications of components. A form factor may represent a broad class of similarly sized components, or it may prescribe a specific standard.

Foundational identification system – A general or multipurpose identification system primarily created to manage identity information for the general population and provide credentials that serve as proof of identity for applications such as national ID, civil registry and population registration.

Four-colour printing
Also known as
Process colour printing/CMYK printing
– Also known as process colour printing – a conventional printing method based on four colours: the so-called CMYK colours of cyan, magenta, yellow and black. Together, these colours can reproduce on paper almost 70% of the colours visible to the human eye.

Fourdrinier machine
Also known as
Flat wire machine
– A papermaking machine consisting of a moving endless belt of wire or plastic screen that receives a mixture of pulp and water and allows excess water to drain off, forming a continuous. Fourdrinier was first machine to produce a continuous web (roll). It is more suited than cylinder mould for producing lightweight paper for documents such as tax stamps. See also Dandy roll.

Frangibility – Capable of being broken. Refers to security labels or tax stamps which break up when removed or tampered with.

Fresnel lens – A type of composite compact lens developed by the French physicist Augustin-Jean Fresnel for use in lighthouses. The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a conventional optical lens. Instead of the curved surface of a conventional lens the Fresnel lens consists of a series of concentric grooves that act as individual refracting surfaces, bending parallel light rays to a common focal length.

Frosting – An effect in which parts of a coin are slightly dulled (using sandblasting techniques) to provide a contrast to the shinier parts of the metal.

Fugitive ink – Solvent- or water-based ink printed onto a security document. When solvent or ink eradicators are applied to the document the fugitive ink spreads out creating a smudge, which denotes the attempt to tamper with the print.

Functional identification system – A sectoral or single-purpose identification system primarily created to manage identity information and provide credentials that serve as proof of identity for applications such as voter registration, tax ID, social security numbers and driving licences.

Fungible – An item is fungible if one unit of the item is equivalent to another unit of the same item of the same quality at the same time, place, etc. Fungibility allows an item or asset to be interchanged with other individual goods or assets of the same type. Fungible assets simplify exchange and trade processes, as fungibility implies equal value between assets.

Furnish – The recipe used to manufacture paper that comprises various pulps, dyes, additives and other chemicals blended together in the stock preparation area of the paper mill and fed to the wet end of paper machines to make paper or paperboard.

Gait – A biometric subject’s manner of walking.

Gas chromatography-mass spectrometry – An analytical method combining gas chromatography and mass spectrometry to identify different substances within a test sample. Used in fuel integrity programmes.

Geolocation – The identification of the geographic location of an object.

Ghost image – A secondary portrait image of a document holder created by laser perforation and visible in transmitted light.

Ghost watermark – An artificial watermark printed on the back of a sheet that will not appear on a scanned or copied document.

Global Trade Item Number (GTIN) – A GS1 standard number unique to each stock-keeping unit (SKU) or specific product type, but not unique to a product at unit level.

Gold standard – Originally a monetary system in which the monetary unit of a country was exchangeable for gold. This evloved to be a fixed quantity of gold on which the issue of paper money was in proportion to the holdings.

Grade – A carefully constructed series of guidelines to determine the condition and therefore the rarity and value of a coin.

Graphene – A single layer of carbon atoms arranged in a hexagonal lattice structure, forming a 2D material with exceptional mechanical, electrical, and thermal properties. It is widely studied for its potential use in fields such as electronics, energy storage, and biomedicine. Graphene is not only the thinnest, but also one of the strongest materials; it conducts heat better than all other materials; it is an excellent conductor of electricity; it is optically transparent, yet so dense that it is impermeable to gases.

Grating – An array of parallel lines with spacing comparable to wavelengths of light. The array has the ability to split white light into a rainbow because the different wavelengths are bent, or diffracted, by different amounts. Such gratings were originally produced by using a diamond to rule closely spaced lines onto glass, but they are now more often produced by optical interference.

Gravure printing
Also known as
Rotogravure printing
– A type of intaglio printing process, which involves engraving an image onto a cylinder. Like offset printing and flexography, gravure uses a rotary printing press.

Grayscale printing – A printing technique that uses varying shades of gray to produce an image. Unlike full colour images created by combining different colours of ink, grayscale images are produced solely from black ink.

Gross issuance – Value of banknotes issued by a central bank over a given period.

GS1 – A not-for-profit organisation that develops and maintains global standards for identifying products, associations, services and localisations and for exchanging data. The best known of these standards is the barcode, a symbol printed on products that can be scanned electronically and that is widely used in supply chains around the world.

GS1-128 barcode – A 1D (linear) alphanumeric barcode for labelling outer packaging and logistics units, such as pallets. Can hold more information than EAN-13 codes.

Guilloche pattern
Also known as
Geometric lathework
– A printed security feature composed of geometric, complex patterns of interlaced or interwoven curved fine lines that are difficult to reproduce using digital print or photocopiers.

Half window – A variety of clear window, with one side of the banknote opacified.

Hamming distance – The number of non-corresponding digits in a string of binary digits, used to measure dissimilarity. Hamming distances are used in many Daugman iris recognition algorithms.

Heat transfer printing
Also known as
Thermal transfer printing
– A method of lamination whereby heat is used to transfer print from one substrate to another. Most US cigarette tax stamps are applied by this method.

High refractive index (HRI) – The refractive index of a material is a dimensionless number that describes how fast light travels through the material. In situations where a transparent hologram is required, for instance as a laminate to cover the variable data of a passport or other ID document, instead of coating the holographic image with a metallic film, a transparent coating is made using a material with a high refractive index. The HRI materials used in this process are typically oxides (eg. titanium dioxide) or sulphides (eg. zinc sulphide). In this way, the light diffracted by the hologram can be seen, as can the variable data underneath.

Hinge – Flexible woven fabric used to attach a polycarbonate biodata card to a booklet ID document, fused into the polycarbonate body of the biodata card.

Hoarding – The use of cash as a store of value. However, the term is sometimes used negatively in the context of concealment to avoid tax or related to other criminal activity. It is often used in the context of the war on cash.

Hologram – The term ‘hologram’ is derived from two Greek words: ‘holos’ meaning whole or complete and ‘graphos’ meaning an image. The term therefore describes a recorded image which is complete, in that it shows, through the diffraction of light, the whole volumetric space of the image – with depth, colour and movement. This is in contrast to a conventional picture, painting or photograph which displays an object from a single viewpoint only.

Holographic avatar – A pre-recorded image that is played back as a projection under controlled lighting and audience conditions.

Holographic optical element (HOE) – An optical device that uses diffraction to shape a wavefront, as opposed to a refractive optical element (using materials with differing refractive indexes) that depends on refraction.

Holoportal – A constructed box or theatre rigging used to create a holopresence effect.

Holopresence – Real-time transmitted realistic images that appear solid to the viewer and that the viewer can interact with.

Hot foil stamping – A method of transferring a foil from a polyester carrier to paper or other substrate through the combination of heat and pressure. Hot foil stamping can be used to support holographic anda other optically variable images which can be transferred, using heat and pressure, onto another substrate such as paper or plastic. The layers containing the image are extremely thin, typically 5-6 microns. Therefore, they need to be supported on a thicker material such as 19-micron thick polyester. The action of stamping the foil with a heated die causes a ‘release’ layer between the image and polyester support to melt, while simultaneously softening an adhesive ‘size’ coating. These combined effects allow the image to leave the polyester support and adhere to its new location.

Hot melt adhesive – An adhesive that is solid at room temperature and becomes liquid when heated. Used to bond two surfaces when cool.

House note – A ‘banknote’ designed and printed by banknote suppliers for promotional purposes, with the supplier’s name usually clearly stated on it. The note serves as a business card demonstrating the suppliers’ capabilities.

Hybrid substrate – A substrate that is a mixture of natural fibres (cotton) and plastic material, without one predominating the other.

Hyperspectral imaging – A technique that collects and processes information from across the electromagnetic spectrum. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in an image, with the purpose of finding objects, identifying materials, or detecting processes.

Identity – A set of attributes that uniquely describe a person.

Identity document – A physical identity credential.

Identity ecosystem – An interconnected set of identification systems – including databases, credentials, laws, processes and protocols.

Identity provider – A government agency or private corporation that issues and manages identities, credentials, and authentication processes.

Illicit trade – The production, distribution or sale of counterfeit, adulterated or diverted goods via illegal and unregulated channels. Also includes the evasion of taxes on legally produced goods.

Illicit whites
Also known as
Cheap whites
– Cigarettes which are legally produced under unique brand names – or no brand name at all – and destined primarily or exclusively for illicit distribution, outside the jurisdiction where they are produced.

Imaging science – A multidisciplinary field concerned with the generation, collection, duplication, analysis, modification, and visualisation of images.

Immunoassay column recognition marker – A biochemical test measuring the presence or concentration of a molecule in an extracted substrate using an antibody or antigen.

Immutability – Blockchain is immutable and transparent. When data is recorded on the blockchain network, it becomes visible to other participants and cannot be changed. All blocks are connected to each other. No-one can delete, edit, revise, rewrite, update or undo, any of the blocks.

Incident light – The light that emanates from a defined light source, such as the sun or a lightbulb, and illuminates an object.

Indicia – Signs, indications, tokens or distinguishing marks.

Induction seal – An aluminium foil or paper seal bonded over the opening of usually bottles after they have been filled with pills or capsules. Provides tamper evidence but can potentially be illegally replaced if plain foils with no security features are used on the original product.

Industry 4.0 – Also called the Fourth Industrial Revolution. The next phase in the digitisation of the manufacturing sector, driven by the rise of data and connectivity, analytics, human-machine interaction, and improvements in robotics.

Infrared light (IR) – The part of the electromagnetic spectrum between 700nm and 1.0mm wavelength. IR light lies immediately beyond red visible light and is therefore invisible to the naked eye. IR light is used in detectors and special equipment to detect security features of banknotes and other documents.

Ingot
Also known as
Lingot
– Metal or metal alloy bar or piece resulting from the process of smelting.

Ink-stained banknote – A banknote that is stained with a special wash-resistant ink, triggered by an anti-theft mechanism located in a cash container or security case locked with a special seal and security key. See also Intelligent banknote neutralisation system.

Inkjet printing – A technique that projects tiny droplets of ink directly onto a substrate, which then penetrates the surface. As there is no printing plate, the technique is favoured for printing variable and personalised data.

Innovation hub – The Bank for International Settlements has set up innovation hubs to explore and exploit the rapid technological changes affecting central banking. The hubs are in Hong Kong SAR, Singapore, Sweden, Switzerland, UK, Germany, France, Canada, and the bank has a strategic partnership with the Federal Reserve System in New York.

Intagio scanning and recognition device (ISARD) – An optical detection system capable of determining the presence of intaglio printing on a banknote.

Intaglio printing – A security printing process that is synonymous with banknote printing but also used on ID documents and some tax stamps. The area of the image to be printed is recessed into the surface of the printing plate via engraving or etching and the recessed areas filled with high-viscosity ink. The excess ink is wiped from the plates and heavy pressure is applied to transfer the ink to the paper. The resulting raised ink profile gives intaglio-printed documents their characteristic tactility.

Integrated circuit – The fundamental building block of all modern electronic devices. An integrated system of multiple miniaturised and interconnected components embedded into a thin substrate of semiconductor material (usually silicon crystal). Also known as a chip or microchip.

Intellectual property (IP) – A category of property that includes intangible creations of the human intellect. There are many types of intellectual property, and some countries recognise more than others. The best-known types are patents, copyrights, trademarks, and trade secrets.

Intelligent banknote neutralisation system (IBNS) – An anti-theft mechanism located in a cash container or security case that is locked with a special seal and a security key. If the security case is stolen, any attempt to open it by force (or without using the correct key) will automatically trigger the mechanism and the banknotes will immediately become recognisable as stolen and should therefore be rejected at any financial institution.

Interbank settlement – The balancing off of bank funds held at a central bank at a given agreed moment at the end of a trading period. If Bank A’s customers have transferred more money to Bank B than Bank B’s customers have transferred to Bank A, then Bank A needs to transfer appropriate funds to even out the balance.

Interchange fee – A fee paid between banks for the acceptance of card-based transactions. For instance, a merchant’s bank (acquiring bank) will pay an interchange fee to the cardholder’s bank (issuing bank) when the latter makes a transaction. This is also the case when a cardholder uses an ATM: the cardholder’s bank pays a fee to the ATM operator.

Interference – The result of the interaction between two superposing waves. Interference pigment flakes are used in colour-shifting inks, and interference foils with colour-shifting properties also exist.

Intermittent magnetic thread (IMT) – A security thread containing an invisible code printed in magnetic ink, which can be used to authenticate and/or denominate banknotes in sorting machines.

International Civil Aviation Organisation (ICAO) – A specialised agency of the United Nations responsible for establishing goals and objectives of traveller identification management.

International Standards Organisation (ISO) – An independent, non-governmental international organisation with a membership of 165 national standards bodies. Through its members, ISO brings together experts to share knowledge and develop voluntary, consensus-based, market-relevant international standards that support innovation and provide solutions to global challenges.

Internet of things (IoT) – A network of physical objects that are embedded with sensors, software, and other technologies for the purpose of connecting and exchanging data with other devices and systems over the internet.

Interoperability – The ability of different information systems, devices and applications to access, exchange, integrate and cooperatively use data in a coordinated manner, within and across organisational, regional and national boundaries.

Interpol – Name of the International Criminal Police Organisation, dating back to 1923. Its activity extends to all crimes of common law and especially those related to drug and gold trafficking, counterfeiting of money and capturing criminals harbouring in a foreign country. Police forces from most countries in the world take part in this organisation.

Intrinsic value – The metal value of a coin or medal.

Iridescence – The ability of some materials to create rainbow effects when they reflect white light. Pearls, oil films on water and bubbles all show iridescence. The effect can be created with foils, ink, and laminates to create optically variable devices.

Iridescent ink – An ink containing (normally) tiny flakes of a shiny silicate mineral (mica) that interferes with incoming light to create a pearl effect on the finished document. Iridescent inks are sometimes used as low-grade security features. They are not the same as colour-shifting inks.

ISO 12931:2012 – An ISO guidance standard for performance criteria for authentication solutions used to combat counterfeiting of material goods. This standard was revised under a new number: ISO 22383:2020.

ISO 14298:2021 – An ISO compliance standard specifying requirements for a security printing management system for security printers. The certifying organisation behind 14298 is Intergraf.

ISO 22376:2023 – An ISO standard for the specification and usage of visible digital seal (VDS) data format for authentication, verification and acquisition of data carried by a document or object.

ISO 22380:2018 – An ISO guidance standard establishing general principles for an organisation to identify the risks related to various types of product fraud and product fraudsters.

ISO 22381:2018 – An ISO guidance standard for establishing interoperability among object identification systems to deter counterfeiting and illicit trade.

ISO 22382:2018 – An ISO guidance standard for the content, security, issuance and examination of excise tax stamps.

ISO 22383:2020 – An ISO guidance standard for the selection and performance evaluation of authentication solutions for material goods.

ISO 22384:2020 – An ISO guidance standard for assessing product security-related threats, risks and countermeasures by developing a suitable protection plan, supporting its implementation and monitoring its effectiveness once implemented.

ISO 22385:2023 – An ISO guidance standard for establishing a framework for trust and interoperability.

ISO 22388:2023 – An ISO guidance standard for securing physical documents.

ISO/CD 22373 – An ISO guidance standard, under development, for establishing trustworthy supply chains for material goods.

ISO/IEC 15459-3:2014 – An ISO/IEC (International Electrotechnical Commission) standard specifying common rules for unique identification required to ensure full compatibility across different identities.

ISO/IEC 20248:2022 – An ISO/IEC (International Electrotechnical Commission) standard specifying a method whereby data stored within a barcode or RFID tag are structured, encoded and digitally signed.

Isotope – Atoms of the same element with the same number of protons (atomic number) but a different number of neutrons.

Isotopic tags – A forensic marker technology that involves adding isotopic variants of one or more components of a formulation or packaging to allow the identification of genuine products.

Issuing authority – The entity authorised to issue money of legal tender in a country. Generally, the expression is synonymous with a central bank or monetary authority. Also refers to government authorities issuing ID documents, tax stamps and other secure documents.

Jackpotting – A fraudulent act where cybercriminals cash out automatic teller machines using extremely sophisticated malware. To pull off this illegal payday, criminals avoid using brute force to dispense cash.

Keys – private and public
Also known as
Lock and key
– A system of encryption whereby a ‘key’ is required to decode a message. The key is usually a handheld device which renders meaningful that which was previously unintelligible. Public keys may be disseminated widely, whereas private keys are restricted to certain individuals, thereby limiting access to the encrypted information. See also Public key infrastructure.

Kinetic – An adjective whose roots in the Greek word ‘kinesis’ indicate motion. A holographic image which displays movement of form or colour is said to be kinetic. Often, such images are patterns rather than objects. The patterns can be made up of fine lines or graphic elements and appear to scintillate when moved.

Kiss cut
Also known as
Rip cut
– A tamper-resistant feature employing a die-cutting process whereby adhesive-backed foils or papers are cut through, but the laminated backing paper is not.

Laminate overprint – An image which is applied on laminate coating to protect it against forgery. Screen printing and gravure printing are the most frequent printing methods used for laminate overprint.

Lamination – The technique/process of manufacturing a material in multiple layers, using heat, pressure, welding or adhesives, so that the composite material achieves improved strength, stability, appearance or other properties. A laminate for ID documents is a mostly clear layer of plastic placed over the information on the ID data page to prevent tampering. The laminate will most often contain visual anticounterfeit features for further protection.

Laser – An acronym of ‘light amplification by stimulated emission of radiation’, a device that produces coherent light by stimulated emission of radiation.

Laser engraving – Pictures and text are engraved in plastic laminates or cards by means of a laser. In the laser engraving process the data are written by blackening (carbonising) laser-sensitive foils. Using different photo-sensitive materials, colours can also be obtained.

Laser perforation – Using energy delivered by a laser, holes of different shapes and sizes can be perforated into a substrate to produce serial numbers and other data, such as in an ID document.

Laser printing – An electrostatic digital printing process that produces text and graphics by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a ‘drum’, which defines a differentially charged image. Laser colour digital copiers use this printing technique. It is a technique used in counterfeiting banknotes and other security documents.

Latent image – An image formed by parallel straight relief strokes perpendicular to background strokes. The image is almost invisible in incidental white light at a right angle. It is visualised as an achromatic image in sliding white light at an acute angle of observation due to the shadow cast by the relief strokes. The background and image are applied by means of intaglio and have the same colour and stroke density.

Latent multicolour image – A latent image formed by multicolour relief strokes. A latent multicolour image is slightly visible in white light. It is visualised as a chromatic image under oblique light. Every chromatic element of the image changes colour when rotating the document around the vertical axe without changing the angle of observation. Background strokes are applied by offset and relief lines by intaglio.

Latent scrambled image – A latent image that has been fragmented and encoded according to a special algorithm. The image is visualised via a lenticular decoding device.

Legal tender – Money that is legally valid for the payment of debts and must be accepted for that purpose when offered. Each jurisdiction determines what is legal tender, but essentially it is anything that when offered (‘tendered’) in payment of a debt extinguishes the debt. There is no obligation on the creditor to accept the tendered payment, but the act of tendering the payment in legal tender discharges the debt.

Legend – The lettering, words or phrases that are engraved on coins, usually located along or around the outside edge of the coins.

Lender of last resort – Central banks usually fulfil the function of ‘lender of last resort’. To ensure financial stability, the central bank provides emergency credit to financial institutions that are struggling financially and near collapse, for example if they no longer have other available means of borrowing, and where their failure to obtain credit would dramatically affect the economy. An example of when this is needed is if bank account holders withdraw funds at a level and in a timespan which means the bank cannot liquidate assets fast enough to match the demand, creating what is known as a ‘run on the bank’.

Lenticular lens – An array of lenses, designed so that when viewed from slightly different angles reveal different parts of an image. The most common example are the lenses used in lenticular printing to give an illusion of depth, or to make images that appear to change or move according to the viewing angle.

Lenticular printng – A multistep process consisting of creating a lenticular image from at least two existing images, and combining it with a lenticular lens. This process can be used to create various frames of animation (for a motion effect), offsetting the various layers at different increments (for a 3D effect), or simply to show a set of alternate images which may appear to transform into each other.

Letterpress printing – A relief printing process by which many copies are produced by repeated direct impression of an inked, raised surface against sheets or a continuous roll of paper. Letterpress printing remained the primary means of printing and distributing information until the 20th century, when offset printing was developed, which largely supplanted the role of letterpress in printing books and newspapers.

Level 1, 2, 3 and 4 security features – A commonly used means of grading security features created by the European Central Bank and adopted for use across the banknote industry. Level 1 refers to features that can be verified by the public, untrained examiners or specialist examiners with the naked eye. Level 2 refers to semicovert features that require some form of reading device or tool to be authenticated. They are typically deployed for use by retailers, cashiers and inspectors but are also detected by sensors in machines (the ECB defines Level 2a, 2b and 2c). Level 3 refers to covert features, generally rare chemicals or compounds that can only be identified by sensors in high speed processing machine verification used in cash centres. Level 4 authentication uses forensic examination to verify banknotes and is used solely by central banks/police.

Light emitting diode (LED) – A semiconductor device that emits light when an electric current flows through it.

Line width modulation – Manipulating the width, length and height of line structures to create image and text effects. Using a higher resolution for the output results in effects not possible with commercially available software.

Liquid crystal – Chemicals that have properties between those of conventional liquids and solid crystals. Orientation of the crystal-like structure of the chemicals results in optically variable effects. Cholesteric liquid crystals have two refractive indices, a property known as birefringence (the ability to rotate the polarisation of incoming light and reflect circularly polarised light either clockwise or anticlockwise). Liquid crystal technology is used for security features that are validated with a polarisng filter.

Luminescence – A collective term for the effects of colour change or other visible characteristics under different sources of illumination.

Machine learning – An umbrella term for solving problems for which development of algorithms by human programmers would be cost-prohibitive, and instead the problems are solved by helping machines ‘discover’ their ‘own’ algorithms, without needing to be explicitly told what to do by any human-developed algorithms. While artificial intelligence encompasses the idea of a machine that can mimic human intelligence, machine learning does not. Machine learning aims to teach a machine how to perform a specific task and provide accurate results by identifying patterns.

Machine vision – The ability of a computer to see. The technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry.

Machine-readable – A security feature requiring an instrument to verify its presence or data content.

Machine-readable travel document (MRTD) – Passports, visas and other travel documents that follow specifications set out in Document 9303 of the International Civil Aviation Organisation (ICAO) to facilitate automatic border management.

Machine-readable zone (MRZ) – The MRZ in a machine-readable travel document contains personally identifiable information in the form of a sequence of alphanumeric characters and the symbol ‘<' spaced over two or three lines. The sequence of characters can be read by document readers to help automate inspection of travel documents.

Magnetic ink – An ink containing ferromagnetic components that have a specific reaction to the external magnetic field. Text or symbols applied by this ink can be identified by special magnetic sensors or visualised by magneto-optic converters. The ink can be applied on security threads and fibres,and used for printing images, serial numbers and barcodes.

Magnetic strip – Thin strip of magnetic material attached to a plastic card and encoded to record and store data.

Mass spectrometry – An analytical technique to quantify known materials and identify unknown compounds within a sample and elucidate the structure and chemical properties of different molecules.

Master case – A shipping unit of tobacco products – usually comprising 25 or 50 cartons.

Matrix code – A 2D barcode (eg. datamatrix, QR code, dotcode), typically square-shaped, capable of representing more data per unit area than a linear barcode.

Medal – Traditionally, a coin-shaped artistic piece with no face value, made for religious, honorary and other commemorative purposes.

Megapixel – One million pixels. The term is used not only for the number of pixels in an image but also to express the number of image sensor elements of digital cameras or the number of display elements of digital displays.

Metallic ink – Printing ink containing metallic components that provide a metallic finish to the applied substrate.

Metallisation – The coating of films or surfaces with a very thin layer of metal using a metal deposition technique. Metallisation is what gives holograms their silver or similar metallic appearance.

Metameric ink pair – A pair of similarly shaded inks, the colour and contrast of which appear virtually identical in normal light, but which have different spectral responses so that, when viewed in another light (such as infrared), one ink displays different effects or colours to the other. In the case of IR pairs, one ink absorbs IR and the other reflects it, and only the IR-reflecting part can be seen through a filter.

Metasurface – electromagnetic – Thin 2D metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions.

Micro-optics – Optical systems that are between a few micrometres (millionths of a metre) and one millimetre in size, including small lenses or arrays of lenses.

Microchip – contact – An integrated circuit embedded into a recessed area on the surface of, for example, an ID card or passport to store and process personal data. A secure document containing a contact microchip must be inserted into a card reader so that the chip can make contact with electrical terminals and allow information to be read.

Microchip – contactless – An integrated circuit embedded under the surface of, for example, an ID card or passport to store and process personal data. The microchip is connected to an aerial (electromagnetic loop antenna) which allows communication with a card reader via electromagnetic waves (RFID). To supply the microchip with energy and to start communication, the card must be in close proximity to the reader.

Microlens – Small lenses, typically only a few microns in size.

Micromirror – Tiny microscopic mirrors created using origination techniques similar to those used for diffractive OVDs (optically variable devices). Micromirrors reflect light in a specific manner defined by the size and orientation of the mirrors.

Micron (µm)
Also known as
Micrometre
– A unit of measurement commonly used in authentication when referring to the thickness or gauge of physical substrates and features. One micron is equal to one millionth (10-6) of a metre.

Microprint
Also known as
Microtext
– Lines, symbols, designs, images or numbers that are printed at dimensions barely perceptible to the unaided human eye but visible at magnifications of between x5 and x10 by (say) a jeweller’s loupe. Microprinting on banknotes usually combines positive and negative characters.

Microstructure – The very small scale structure of a prepared surface of a material as revealed by a microscope above 25× magnification. Diffractive microstructures comprise microprotrusions or microgrooves, or a combination thereof, which are capable of diffracting lightwaves.

Mining – The process by which new cryptoassets enter into circulation and new transactions are confirmed by a blockchain network. Mining is performed using sophisticated hardware that solves a complex computational maths problem. When a problem is solved, the miner is awarded the next block of cryptoassets and the process recommences with a trickier problem. Computers verify transactions on the blockchain ledger in exchange for a reward based in cryptocurrency.

Mint – An industrial facility manufacturing coins.

Mint mark – A letter or symbol, indicating a mint of origin.

Minting – An alternative to mining, the process by which assets are written to a blockchain, where the writer of the asset is a pre-determined trusted entity. In certain use cases, such as an ecosystem of banks, minting is preferred due to performance and power consumption requirements.

Mixed fibres – A fibrous composition of the substrate used for banknotes, containing fibres of cotton and other materials such as linen or polyester. The purpose of using mixed fibres is to improve the mechanical properties of the paper, such as scratch or crinkle resistance.

Mobile driving licence – A digital driving license held within, and presented from a mobile device.

Mobile identity – A digital identity held within, and presented from a mobile device.

Mobile money – A mobile payments system based on accounts held by a mobile operator and accessible from subscribers’ mobile phones.

Mobile wallet – An app for storing financial information and other documents such as credit cards, bank information, and even driving licences.

Moiré pattern – Large-scale interference patterns produced when a partially opaque ruled pattern with transparent gaps is overlaid on another similar pattern. For the moiré interference pattern to appear, the two patterns must not be completely identical, but rather displaced, rotated, or have slightly different pitch.

Monetary aggregates – Broad categories that measure the money supply in an economy. In the US, labels are attributed to standardised monetary aggregates: M0 – physical paper and coin currency in circulation plus bank reserves held by the central bank; M1 – all of M0 plus traveller’s cheques and demand deposits; M2 – all of M1 plus money market shares and savings deposits.

Monetary law – Monetary law is the legislative and regulatory framework that provides the legal foundations for the use of monetary value in society, the economy and the legal system.

Money – From the Latin word ‘moneta’, money is any item that is generally accepted as payment for goods and services and repayment of debts, such as taxes, in a particular region, country or socio-economic context. Its onset dates back to the origins of humanity and its physical representation took on very varied forms until the appearance of metal coins. The banknote, a typical representation of money, appeared in the 17th century, and has since experienced great development and growth. Currently, electronic systems allow payments without the need to deliver physical money (banknotes or coins). Money is considered to have three basic functions: unit of account, medium of exchange and store of value.

Money laundering – The illegal process of making large amounts of money generated by a criminal activity, such as drug trafficking or terrorist funding, appear to have come from a legitimate source. The money from the criminal activity is considered dirty, and the process ‘launders’ it to make it look clean

Mule – A coin, token or medal whose obverse design is not matched with its reverse.

Multichannel image – A diffractive image in which different, usually unrelated images appear at different viewing angles. The most usual, and easiest to make, are images that flip from one to another as a DOVID is tilted from side to side. The most difficult is an image that changes as the DOVID is rotated.

Multifactor authentication – A multistep account login process that requires users to enter more information than just a password. For example, along with the password, users might be asked to enter a code sent to their email, answer a secret question, or scan a fingerprint.

Multispectral imaging – Captures image data within specific wavelength ranges across the electromagnetic spectrum. The wavelengths may be separated by filters or detected with the use of instruments that are sensitive to particular wavelengths, including light from frequencies beyond the visible light range (ie. infrared and ultraviolet). Multispectral imaging can allow extraction of additional information the human eye fails to capture with its visible receptors for red, green and blue.

Nanometre (nm) – A unit of measurement commonly used in authentication when referring to the thickness or gauge of physical substrates and features. One nanometre is equal to one billionth (10-9) of a metre.

Nanotechnology – The science and technology of precisely manipulating the structure of matter at the atomic and molecular level. In the authentication sector, nanotechnology is used to explore and develop unique optical phenomena for use in new material and security features.

National central bank (NCB) – In general, refers to the central banks of different countries that are part of a currency union.

National identification system – A foundational identification system that provides national IDs – often an identity document – and potentially other credentials. In many countries, a primary function of national ID systems has been to establish and provide recognition and proof of nationality and/or residency status.

Near-field communication (NFC) – A method of wireless data transfer between two electronic devices over a distance of 4cm or less.

Near-infrared – The part of the electromagnetic spectrum between 780nm and 2500nm, near-infrared is the region closest in wavelength to the red light detectable by the human eye.

Negative interest rate – When the nominal interest rate drops below 0% for a specific economic zone. This effectively means that banks and other financial firms have to pay to keep their excess reserves stored at the central bank, rather than receiving positive interest income. This is hard to enforce while people have the option to hold funds in other assets, particularly physical cash.

Net issuance – The value or units of banknotes (or coins) issued by a central bank over a period, minus the equivalent withdrawn from circulation during the same period. A positive net issuance expresses an increase in circulation during the period.

Node – Computers in a cryptocurrency network.

Nominal value – The value stated on a coin or banknote, ie. face value.

Non-fungible token (NFT) – A unit of data stored on a blockchain digital ledger that certifies a digital asset to be unique and therefore not interchangeable Used to represent ownership of real-world unique items like art, video clips and music – unlike money or bitcoin, which are fungible.

Notaphily – The study of paper money or banknotes.

Notes held to order (NHTO) – System used in some countries in which the central bank delegates the safekeeping and distribution of banknotes to private entities and offers some sort of financial compensation to incentivise the system. See also Balance sheet relief mechanism.

Numbering – Numbering enables a banknote to be differentiated from another banknote of the same denomination. If two banknotes have the same numbering it is proof that one of them is false. Numbering is usually on one side of the note, but can be on the front or the back.

Numismatic value – A price that is given to a numismatic object. It may deviate from the face value as a result of various factors: the degree of rarity, the state of the object’s preservation, the artistic relevance and the historical significance.

Numismatics – The science, study or collecting of coins, medals, paper money and related objects. In the scope of banking services, the numismatic service deals with the sale of legal, former or rare banknotes and coins to customers with collecting interests.

Numismatist – A collector or knowledgeable person in the field of numismatics.

Object beam – A wave reflected from an object and incident on a usually photosensitive material. Also refers to the beam that is transmitted and diffracted by a holographic plate (H1) which becomes the ‘object’ from which a copy (H2) is made. See also Reference beam.

Oblique light – Light from the side, falling at a shallow angle, and revealing the surface structure of an object through contrasts of light and shade. Oblique light is used especially to inspect embossing stamps, intaglio printing, latent images and mechanical erasures.

Obverse – With a banknote, this is the main side that portrays the most representative motif, often the effigy of a ruling monarch or state symbol. With a coin, it is also the main side or face where a state symbol or portrait of the monarch and name of the country usually appear. The front side of a coin is commonly called ‘heads’ in coin tossing, while the other side is called ‘tails’.

Off-axis laser interferometry – The off-axis method is an origination technique where a laser beam is split into two beams: an object and a reference beam. The object beam illuminates the object/artwork and is scattered onto a photoresist. The reference beam is directed onto the photoresist from the same side but at a different angle (off-axis). The two beams meet and overlap at the photoresist, generating an interference pattern which, in essence, provides a three-dimensional holographic record of the object.

Offset printing
Also known as
Lithography
– An indirect printing process whereby ink is spread on a metal plate with etched images, then transferred to an intermediary surface such as a rubber blanket, and finally applied to the substrate by pressing that substrate against the intermediary surface. With wet offset, the printing plate must be moistened with water before it is inked, whereas dry offset printing does not use water. Offset is often used in long secure document print runs and is the most common printing method for tax stamps.

One-to-many matching – A method for identifying an unknown individual, via biometric data such as a photo of their face or fingerprints, which is compared to a larger database to uncover a potential match.

Opacity – The optical property of a substrate that prevents transmission of light.

Optical character recognition (OCR) – The reading and recognition of characters using an optical device.

Optical phone authentication (OPA) – Process to check security features visible with simple smartphone cameras, such as diffractive motion effects based on the viewing angle.

Optical scanner authentication (OSA) – Allows static controls using cameras at multiple wavelengths (visible and infrared light).

Optically variable device (OVD) – Overt and semicovert security features with dynamic characteristics that change according to the viewing angle – eg. from one colour to another, or from one image to another.

Optically variable ink – A popular type of secure printing ink that contains microscopic pigments acting as interference filters, resulting in large colour shifts determined by the angle of lighting or viewing.

Origination – The process which transforms an initial design of a banknote or security document into an industrial product ready for printing.

Orlov printing – A single-run multicolour printing method invented by Ivan Orlov in 1890 in Russia. Consists of creating separate ink layers on colour-separated plates and transferring the inks to a common plate and then to the receiving surface.

Other tobacco products (OTP) – Tobacco products other than cigarettes, such as cigars and pipe tobacco.

Overt security feature
Also known as
Level 1 security
– Security features such as holograms that are apparent to the human senses – especially those of sight and touch – without the need for additional readers and instruments. Such features are designed to enable all stakeholders, including the public, to identify if something is genuine or not.

Pantone – Name of a widely used colour matching system in graphic design, whereby each colour is coded with a reference number.

Paper – The most widely used banknote substrate throughout history, usually made from cotton, with short fibres that give a banknote special characteristics of touch, sound and firmness. It can also include other fibres of different origins.

Parallax – The phenomenon in an image which allows depth to be judged from the movement of near image elements relative to more distant ones. Traditional embossed holograms only display parallax from side to side, but the lack of vertical parallax is rarely noticed. Ortho-parallax is the term for when the movement of the elements is in a counterintuitive direction (ie. 90°) to the angle of view.

Passive security feature – A security feature that requires an action such as scanning or photocopying to become visible. See also Active security feature.

Passport – This is the main document certifying a person’s identity and allowing them to cross a border. A passport is issued to all individuals who are citizens or permanent residents of a particular country. It consists of a small book with a hard or a soft cover. It contains the holder’s personal identifying information, security features, information about the issuing country and issuing authority, and blank pages for visas and other marks.

Payload – In computing and telecommunications, the payload is the part of transmitted data that is the actual intended message.

Payment instrument – Documents that can be used legally to effect payment in commercial banks in book money or currency. For example, cheques, bills of exchange, promissory notes.

Payment rail – A payment platform or network that moves money from payer to payee. Credit card rails are the credit card payment system.

Payment Service Provider (PSP) – Traditionally, PSPs have provided shops with online services for accepting electronic payments by a variety of payment methods including credit card, bank-based payments such as direct debit, bank transfer, and real-time bank transfer based on online banking. Typically, these are a software-as-a-service model and form a single payment gateway for clients (merchants) to multiple payment methods. For central bank digital currencies, PSPs are likely to facilitate the acceptance and use of CBDCs for payments.

Pearlescence – Visibly similar to iridescence but with a slightly ‘milky’ appearance at certain viewing angles.

Peer-to-peer – Peer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the application. They are said to form a peer-to-peer network of nodes.

Permissioned blockchain – An additional blockchain security system that maintains an access control layer to allow certain actions to be performed only by certain identifiable participants.

Personalisation – In the context of ID, personalisation refers to the combination of biographical data, variable text and signature that are added to a document to render it unique and link it to the document holder.

Phishing – The fraudulent practice of sending emails or other messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers.

Phosphorescence – A type of fluorescence that continues for a period of time after the stimulus that produced the emission has stopped.

Photochromism – A light-induced reversible colour change which in its most familiar form involves an ultraviolet-induced transformation from colourless to coloured. Sunglasses that darken in the sunlight and revert to near colourless in subdued light constitute the most widely known application of photochromism. However, there are a diverse range of other applications and potential applications that include fuel markers, security inks and electronic nanotechnology.

Photoluminescence – Luminescence produced by exposure to ultraviolet light.

Photopolymer hologram – Holograms produced from materials that polymerise (combine to form a polymer) under the action of light energy and thus change their refractive index. Used to record volume reflection holograms (see Volume hologram).

Photoresist
Also known as
resist
– A light-sensitive material used in processes such as photolithography and photoengraving to form a patterned coating on a surface. A substrate is coated with a light-sensitive organic material. A patterned mask is then applied to the surface to block light, so only unmasked areas are exposed. A solvent, called a developer, is then applied to the surface. In the case of a positive photoresist, the photo-sensitive material is degraded by light and the developer dissolves away exposed areas, leaving a coating where the mask was placed. In the case of a negative photoresist, the photo-sensitive material is strengthened (either polymerised or cross-linked) by light, and the developer dissolves away areas not exposed to light, leaving a coating in areas where the mask was not placed. This process is used to create surface grating images, which are the first stage in producing embossed holograms.

Physical unclonable function (PUF)
Also known as
Document biometrics/ document fingerprinting
– A device that utilises the unique, random, physical variations which occur naturally in a physical structure and which provide that structure with a ‘fingerprint’ that serves as a unique identifier. See also Fingerprinting – document.

Physical vapour deposition (PVD) – A range of technologies whereby a material is released from a source and deposited on a substrate using a mechanical, electrochemical or thermodynamic process.

Pickling – A process in which coin blank proofs are cleaned in acid to remove oil, directional rolling lines and dirt from their surface.

Piracy – The illegal reproduction and distribution of copyright material, generally taken to be audio and video content.

Pixel – In digital imaging, a pixel (or picture element) is the smallest item of information in an image. Pixels are arranged in a 2D grid, represented by squares. Each pixel is a sample of an original image, with more samples typically providing more accurate representations of the original.

Planchette – A coloured or reflective disc containing a security feature and embedded in paper during manufacture.

Plasma – Plasma is superheated matter – so hot that the electrons are ripped away from the atoms, forming an ionised gas. It comprises over 99% of the visible universe. In the night sky, plasma glows in the form of stars. That branch of lightning that cracks the sky is plasma. So is the sun… and so are neon signs on city streets. Plasma is often called ‘the fourth state of matter’, along with solids, liquids and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma – a soup of positively charged particles (ions) and negatively charged particles (electrons).

Plasmon – In physics, a plasmon is a quantum of plasma oscillation. Just as light consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantisation of plasma oscillations,

Plasmonics
Also known as
Nanoplasmonics
– The generation, detection, and manipulation of coherent electron oscillations (known as surface plasmon polaritons), as they travel together with an electromagnetic wave along the interface between a metal (eg. silver, gold) and a dielectric material (eg. glass, air) at the nanometric scale. Inspired by photonics, plasmonics follows the trend of miniaturising optical devices, and can be applied as a security feature. The plasmons can be controlled through careful modelling and application of, among other things, the dielectric and metal layer thickness in a ‘sandwich’ structure. When the sandwich structure is applied as a device to a security document, it allows light that falls on the surface of the device to be controlled in terms of its wavelength (allowing control over the colour) and amplitude (giving rise to the intensity, or brightness of the colour generated).

Plaster – A model made during the coin design process, approximately four times larger than the actual size of the final coin or medal.

Point-of-sale terminal (POS terminal) – A device allowing the use of payment cards at a physical (not virtual) point of sale. The payment information is captured either manually on paper vouchers or by electronic means.

Polarisation – The alignment of the electric and magnetic fields in a particular orientation in a lightwave. If all the waves in a beam of light move up and down or from side to side together, the beam is said to be plane-polarised. Some materials have the ability to filter out all lightwaves except those in a particular direction. Other materials are said to be optically active if they are able to change the angle of a plane-polarised beam of light. Liquid crystals often have this property and this enables them to be detected.

Polarising filter – An optical device which transforms unpolarised light into polarised light. It is used to examine light reflected from ink or thin-film coating. It blocks light rays of a specific polarisation direction while letting light rays of other polarisation directions pass.

Polycarbonate (PC) – An increasingly popular thermoplastic polymer used as the substrate of choice for ID cards and the data pages of passports, due to its durability, high dimensional stability and transparency. It also lends itself to laser engraving and ablation for additional security features.

Polyethylene terephthalate (PET) – A thermoplastic polymer resin of the polyester family, used to make the most common container in the soft drink market today: the plastic bottle. Also used as the base material for most surface-applied holograms and security threads.

Polymer – A substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits. Plastic and polyester are all polymers. Polymer banknotes were first introduced in Australia and are widely used around the world.

Polymerase Chain Reaction (PCR) – A laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail.

Polymerisation – The act of converting a paper banknote design for use with polymer substrate.

Polyvinylchloride (PVC) – A thermoplastic polymer used as a substrate in many documents. However, polycarbonate is often preferred as a substrate for security printing and documents requiring high durability.

Portable data file 417 code (PDF 417) – A stacked linear barcode format used in a variety of applications such as transport, identification cards, and inventory management. The ‘417’ signifies that each pattern in the code consists of 4 bars and spaces in a pattern that is 17 units (modules) long.

Precautionary holding – The holding of banknotes/CBDCs as a store of value, for saving purposes or as a precaution for uncertainties.

Prepress – Preparatory work required on original materials, such as films, files and plates to carry out the printing of a banknote or other security document.

Pressure-sensitive application – A label construction made up of three layers: a face material, a pressure-sensitive adhesive, and a backing sheet coated with a release agent. Pressure-sensitive labels only need the pressure of a hand to be applied to an item.

Print registration – In colour printing, print registration is the layering of printed patterns to form a multicolour image. Registration error refers to position misalignment in overlapped patterns, resulting in printed colours in the wrong areas, overprint or white space.

Printworks – A plant for producing banknotes and other security documents. Printworks can be either state or central bank-owned or run by commercial companies.

Prismatic pattern – The overprinting of two or more coloured inks to create a blended colour affect that is difficult to match on copiers. Prismatic colour blending is visually similar to split fountain printing, but differences become apparent when the images are magnified.

Private distributed ledger (Private DLT) – Private DLTs are open to participants approved by a central authority with control over the DLT network and its design. Information regarding the private DLT is not usually available outside the network.

Private key – A secret key that must only remain known to the recipient. A private key is somewhat comparable to a pin or verification code.

Private money
Also known as
Commercial bank money
– Money held in the form of deposits and used for lending by a commercial bank.

Production monitoring system – An automated system installed on product manufacturing lines, using sensors and scanners to provide tax authorities and other government agencies with full visibility on what is being produced and ensure that every production unit has been affixed with a valid unique identifier, tax stamp, or secure label.

Programmable payment – The ability to apply a coded instruction automatically to a digital payment so that if set conditions are met, an action then happens. It is most often the payment that is programmable and not the money used to make that payment, but the distinction between the two is still being sorted out. See also Smart contract.

Proof coin – A carefully struck coin using special dies, with frosted images on a mirror-like background. Proof refers to a method of manufacture, not a condition or grade.

Proof of stake – In cryptocurrency, proof of stake uses a deterministic algorithm based on the number of coins owned by a user. This algorithm offers the possibility for nodes to increase their chances of being elected to mine more coins and encourages coin owners to maintain the network because the choice is random. The more coins owned, the higher the chance of being chosen. See also Proof of work.

Proof of work – In cryptocurrency, proof of work solutions refer to transactions secured through a linear trail of transaction history and the use of a computational puzzle (‘proof of work’ consensus algorithm) which reflects that work.

Proof of work – mining – A protocol for verifying cryptocurrency transactions. Nodes use their computing power to prove themselves sufficiently trustworthy to be allowed to add new information about transactions to the network.

Public key infrastructure (PKI) – A set of policies, processes, server platforms, software, and workstations used for administering public key certificates and public-private key pairs, including the ability to issue, maintain, and revoke certificates.

Public money – Money that is issued and held by a central bank.

Public Register of Authentic identity and travel Documents Online (PRADO) – A multilingual site with information on authentic identity and travel documents in the EU. Document descriptions include technical descriptions of some of the most important security features on the document. Document experts in all EU member states as well as Iceland, Norway and Switzerland provide and select the information to be released to the general public via PRADO.

Public-private partnership (PPP) – A cooperative arrangement between two or more public (ie. government) and private sector entities.

Pulp – A fibrous material produced by mechanically or chemically reducing plants to their component parts from which pulp, paper and paperboard sheets are formed after proper slushing treatment.

Quantum computing – A computer that uses specialised technology – including computer hardware and algorithms that take advantage of quantum mechanics – to solve complex problems that classical computers can’t solve, or can’t solve quickly enough.

Quantum dot (QD)
Also known as
Semiconductor nanocrystal
– Semiconductor particles a few nanometres in size with optical and electronic properties that differ from larger particles due to quantum mechanics. Quantum dots may be ‘tuned’ to provide specific visual effects.

Quantum mechanics – A fundamental theory in physics that describes the behaviour of nature at and below the scale of atoms. It is the foundation of all quantum physics.

Quick response code (QR code) – A type of 2D matrix barcode which stores information as a series of pixels in a square-shaped grid. Typically, smartphones are used to scan QR codes, displaying an image of the code and converting it to, say, a standard URL for a website. QR codes can store up to 4,296 alphanumeric or 7,089 numeric characters and are clearly distinguished from datamatrix barcodes by large squares placed at three corners of the code, which are used for alignment. Compared to standard UPC barcodes, QR codes offer faster reading of the optical image and greater data storage capacity in applications such as product tracking and item identification.

Quishing
Also known as
QR phishing
– An act of cybersecurity fraud using QR codes to redirect victims to malicious websites or prompt them to download harmful content. The goal of this fraud is to steal sensitive information, such as passwords, financial data, or personally identifiable information, and use that information for other purposes, such as identity theft, financial fraud, or ransomware.

Radio frequency identification (RFID) – A wireless, non contact technology that uses radio waves to transfer data and passively identify a tagged object. RFID systems are usually comprised of an RFID reader, microchip tags, and antennas. The reader gives off radio waves and gets signals back from the tag, while the tag uses radio waves to communicate its identity and other information. The tags are now so small that they can be neatly implanted into paper. They can typically be detected at distances ranging from a few millimetres to several metres. RFID is used in various commercial and industrial applications, including tracking items along a supply chain.

Rainbow – A rainbow is the visual result of splitting white light into its constituent colours according to wavelength. The order of the colours is red, orange, yellow, green, blue, indigo, violet – with red having the longest wavelength and violet the shortest. The natural phenomenon is caused by the prismatic effect of raindrops in the sky but it can also be caused by diffractive gratings with a spatial frequency approaching the wavelength of light.

Rainbow hologram – When illuminated with incandescent (white) light, rainbow holograms display images bathed in a changing rainbow spectrum of colours as the viewer moves their eyes up and down. Holographers have developed considerable control over the colours displayed in this type of hologram to produce images in a specific colour or in near natural colour.

Rainbow printing – A form of offset security printing involving the split duct process, which results in a gradual change of two specific colours.

Raster graphic – A 2D picture represented as a rectangular grid of pixels.

Rasterisation – The task of converting a vector graphic image into a raster image (ie. a series of pixels, dots or lines which recreate the vector image). The higher the resolution, the greater the number of pixels per unit area. Raster images are used for ensuring a smooth transition of colours and shades, with the most common use being for processing photos. The most popular raster graphics editor is Photoshop.

Real time gross settlement (RTGS) – A funds transfer system that allows the transfer of money or securities instantaneously. In most cases, RTGS is used for high-value interbank transactions that need to be cleared as soon as possible.

Real time payment (RTP) – Refers to payment rails (platforms or networks via which payments are made) that are real-time, or at least very close – initiating, clearing, and settling in a matter of seconds.

Ream – A pack of 500 sheets of paper or other substrate.

Recirculating ATM
Also known as
Recycling ATM
– A self-service ATM that checks deposited banknotes, sorts them and pays out fit notes to customers withdrawing banknotes.

Recombination – A ‘step and repeat’ process whereby a single diffractive image is laid out in rows and columns in preparation for shim production. It can either be carried out mechanically or optically. In the mechanical process, the single image is made into a stamper which is impressed at predetermined intervals, into a plastic sheet. If done optically, the single image is exposed in a predetermined pattern onto a (glass) plate coated with a photoresist.

Red, green and blue (RGB) – A system representing the colours used on a digital display screen. Red, green and blue can be combined in various proportions to obtain any colour in the visible spectrum.

Redenomination – The recalibration of a country’s currency, typically due to hyperinflation and currency devaluation, whereby an old currency is exchanged for a new one at a fixed rate.

Reeding
Also known as
Milling
– A technique wherein a number of narrow ridges called reeds are carved or milled into the edges of coins. Reeding was originally undertaken as an anticounterfeiting measure to prevent gold and silver coins from being clipped. The technique is still used as an anticounterfeiting measure, and to help the visually impaired differentiate between coin denominations.

Reference beam – An unmodulated beam which, when directed at a photoresist forms a stationary interference pattern with the object beam. See also Object beam.

Reflected light – The bouncing of light off an object (as opposed to light that transmits through or is absorbed by an object).

Reflection hologram – A hologram that is viewed by the reflection of white light. The diffractive planes within the depth of the recording material have a spacing which corresponds only to a single wavelength of light. This wavelength, usually green or yellow, is reflected back and reconstructs the image, the other colours being transmitted and absorbed by a black backing placed behind the hologram.

Refraction – The bending of light as a beam passes from one medium (say air) to a different medium (say glass). For applications of refraction see High refractive index.

Registration black – The darkest black that can be made from the four CMYK ink colours, consisting of 100% cyan, 100% magenta, 100% yellow, and 100% black.

Relying party – An entity that relies upon the credentials and authentication mechanisms provided by an ID system, typically to process a transaction or grant access to information or a system.

Replacement banknote – A note printed with a special symbol before the serial number, or with a special serial number prefix, used to replace notes damaged during the manufacturing process.

Replenishment rate – The inverse indicator of the average life of a banknote: the higher the replenishment rate of the note, the lower its average life.

Request for information (RFI ) – A common business process for collecting written information about the capabilities of various suppliers. Normally, an RFI follows a format that can be used for comparative purposes. An RFI is primarily used to gather information to help make a decision on what steps to take next. RFIs are therefore seldom the final stage of procurement and are instead often used in combination with a request for proposal (RFP) and request for quotation (RFQ).

Request for proposal (RFP) – A document that solicits a proposal from suppliers, often as part of a bidding process, by an agency interested in procuring a commodity or service. An RFP is used when a general need or problem must be solved, and potential sellers are proposing solutions and how much they will cost. Companies evaluating an RFP must consider not only the cost but the effectiveness of the solution.

Request for quotation (RFQ) – A document that solicits quotations from suppliers often as part of a bidding process, by an agency interested in procuring a commodity or service. An RFQ is used when a quote is needed for a specific need and solution.

Reserve asset – Financial assets denominated in foreign currencies and held by central banks, which are primarily used to balance payments.

Retroreflection – Occurs when a surface returns a large portion of directed light back to its source, from a much wider angle than a reflective surface. Retroreflective material is made using microlenses (microspheres).

Retroreflective laminate – A security film laminated to the surface of documents such as driving licences and ID cards. Can carry primary images viewable under both ordinary diffuse lighting and retroreflective viewing conditions, as well as retro-images that can only be seen under retroreflective conditions, eg. with a flashlight or specialised retroviewer.

Reverse – The back of the banknote or coin. Referred to as the ‘tails’ side in coin tossing.

Rim – A raised area of metal around the edge of a coin, intended to protect the rest of the coin from wear. Blanks are rimmed before they are struck as coins

Rotary printing press – A printing press where the images to be printed are curved around a cylinder. There are three main types of rotary press: offset (including web offset), rotogravure, and flexography.

Roundtripping – Also called returning exports, where products are manufactured and designated for export, then exported in order to avoid domestic taxes, and subsequently smuggled back into the original jurisdiction.

Sand dollar – The informal name of the Bahamian CBDC.

Schablon
Also known as
Chablon
– The schablon (stencil) multiple colouring process is used in intaglio printing to enable more than one colour to be printed simultaneously and accurately with one printing plate. The individual colours are applied via individual stencils that match the elements or parts of the required final design. The inks may overlap to a small extent and in the final printed image a slight colour transition can therefore be seen.

Scratch-off – A process to cover printed data with a opaque covering so it cannot be read until the final user removes the coating to read the data. Scratch-off ink is often used on lottery tickets to conceal winning numbers.

Screen printing
Also known as
Silkscreen printing
– A process that uses a fine mesh with an impermeable coating, selected areas of which have been removed to allow ink to pass through. Screen printing produces a thick ink layer ideal for printing optical effect security features.

Secure track and trace – The integration of physical and digital security features into a track and trace system to ensure that illicit traders are not able to, for instance, generate their own, functioning, unique identifying codes, nor copy existing codes, nor access confidential information contained in or linked to those codes. The difference between commercial parcel tracking systems and systems used for government-regulated products such as cigarettes, is one of security. Parcel tracking systems are at less risk of being manipulated by parties within the distribution chain than systems used to track cigarettes and other products exposed to illicit trade.

Security fibre – Inclusions added to security paper during manufacture comprising randomly distributed short thin fibres with specific optical or spectroscopic properties.The fibres can be made of silk, plastic or metal, and may be visible, invisible, multicoloured or fluorescent under UV light.

Security paper – Paper typically manufactured from wood pulp or cotton containing security features such as watermarks and security fibres.

Security thread – Polyester threads that are either fully or partially embedded down the length of paper during the paperforming process. Fully embedded threads – typically less than 1.8mm wide – can only be viewed when the document is held up to the light. Partially embedded threads appear intermittently on one side of the paper. Their size is typically up to 4mm wide and they act as carriers for a range of overt security features.

See-through register – A security feature that, when held up to the light, combines elements of the front and back of a banknote or secure document into a specific image.

Seigniorage
Also known as
Seignorage
– Derived from the French expression seigneuriage, referring to the right of the lord (seigneur) to mint money. In the context of banknotes, seigniorage refers to the interest earned by the central bank when investing funds received via issuance of banknotes at face value, minus the cost of producing, distributing and replacing them.

Semiconductor – A semiconducting material has an electrical conductivity value falling between that of a conductor, such as metal, and an insulator, such as glass. Semiconductive inks can be used to create printed antennae.

Semicovert security feature
Also known as
Level 2 security
– A security feature requiring simple, sometimes commercially available tools to view it, such as ultraviolet (UV) lights, polarising filters, magnifiers and lenses. The examiner needs to know where the features are and how to examine them and they are not normally made known to the general public.

Serialisation – The application of a unique identifier to each unit in a lot or batch. The identifiers are numbers but might be printed as alphanumerics or barcodes or might be embedded in a chip activated by radio frequency (RFID). The numbers may be sequential or randomly generated; what is important is that the same number should not be used twice.

Sheetfed printing – A printing press that requires sheets (as opposed to continuous rolls or webs) to be fed into the press prior to printing.

Shim – The first step in mass hologram production is to create embossing plates called shims. A shim is made from a thin plate of metal, usually nickel, which is attached to the embossing cylinder. A ‘master’ or ‘mother’ shim is produced by an electro-deposition process whereby the plate with recombined images is immersed into a galvanic tank and metallic nickel is caused to accumulate on its surface. The mother shim is then usually used to prepare ‘daughter’ shims for the mechanical embossing process.

Shim line – At some point in the hologram replication process, one or more metal shims need to be mounted around the circumference of the embossing cylinder. The point at which the shims join often produces a visible line in the resulting embossed film. This line is most problematic where the finished result is intended to be a continuous pattern. Those skilled in the art have developed procedures which successfully minimise or even eliminate such optical discontinuities in the final product.

Short former
Also known as
Twin former
– A papermaking machine which forms a thicker carrier sheet, on top of which is placed a second ‘laminated’ sheet. Wide security threads – either embedded or ‘windowed’ – can be incorporated between the sheets with little or no reduction in paper strength.

Shortwave infrared light – A subset of the infrared band in the electromagnetic spectrum, covering wavelengths from 1.4-3 microns. Unlike midwave infrared (MWIR) and longwave infrared (LWIR) light, which is emitted from the object itself, SWIR is similar to visible light in that photons are reflected or absorbed by an object, providing the strong contrast needed for high resolution imaging.

Single note inspection (SNI) – An inspection process that examines the visible and machine-read properties of newly printed banknotes before being issued. The process is used to reclaim good notes from defective sheets that, despite being fit for circulation, would otherwise be destroyed.

Sizing agent – A coating mixture applied to paper or other substrate to improve printing or surface properties.

Skimming – Skimming occurs when devices illegally installed on ATMs, point-of-sale terminals, or fuel pumps capture data or record cardholders’ PINs. Criminals use the data to create fake debit or credit cards and then steal from victims’ accounts.

Smart card – A plastic card with a built-in microprocessor, used typically for electronic processes such as financial transactions and personal identification.

Smart contract – A self-executing contract with the terms of the agreement between buyer and seller directly written into lines of code. The code and the agreements contained therein exist across a distributed, decentralised blockchain network.

Smart glasses – Smart glasses integrate wireless networking and images into the frames and lenses of eyewear, just as with home computers and smartphones.

Smart safe – A device for making the cash management of a retailer more efficient. Banknotes and/or coins deposited into the device are counted and provisionally credited to the account holder. The retailer does not have access to the contents of the safe, which is usually serviced by a cash management company.

Smartphone – A cellular (or mobile) telephone with an integrated computer, camera, and other features not originally associated with a mobile phone.

Smishing
Also known as
SMS phishing
– the fraudulent practice of sending text messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords or credit card numbers.

Smuggling – The illegal transportation of objects, substances, information or people across an international border, in violation of applicable laws or other regulations, often to avoid taxation.

Soiled – A banknote that has become dirty through usage, usually from greasy materials sticking to the surface or from the absorption and adhesion of dust and particles to the cotton fibres of the note. Soiling is one of the main reasons for banknote deterioration and subsequent destruction.

Sorting – The process of fitness sorting of banknotes by their condition of use. Through this process, used banknotes are classified as fit or unfit to return into circulation.

Specimen – A sample banknote with no value that is legitimate and numbered, and marked by printing ink or perforation system with the word ‘specimen’. Specimens are exchanged among monetary authorities and in the past sent also to correspondent banks to share information on a new banknote or new series.

Speckle pattern – Produced by the mutual interference of a set of coherent wavefronts. Speckle patterns have been used in a variety of applications in microscopy, imaging, optical manipulation and document biometrics (or fingerprinting). They typically occur in diffuse reflections of monochromatic light such as laser light.

Spectroscopy – The study of the absorption and emission of light and other radiation by matter. Involves the splitting of light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), which is done in much the same way as a prism splitting light into a rainbow of colours. More recently, the definition has been expanded to include the study of interactions between particles such as electrons, protons, and ions, as well as their interaction with other particles as a function of their collision energy.

Split duct process
Also known as
Rainbow printing
– A process employed in offset printing where colours are intentionally allowed to overlap on the transfer cylinder producing a gradated effect.

Spoofing – Spoofing involves faking one’s identity, and can be used for various attacks such as identity theft. Phishing is one such use of spoofing that attempts to steal somebody’s personal information or credentials by having them volunteer that information from a nefarious source that looks legitimate.

Spot colour
Also known as
Solid colour
– Any colour printed with its own ink, in contrast to process colour printing which uses four inks (cyan, magenta, yellow and black – or CMYK) to produce all other colours.

Stablecoin – A cryptocurrency backed by a reserve asset. The backing aims to provide confidence so that stablecoins can be used for instant processing, offering security or privacy but without the volatility of cryptocurrencies such as bitcoin.

Stamp – An impression, mark or relief formed on a paper substrate by means of pressure from a stamp.

Steganography – The practice of representing information within another message or physical object so that its presence is not evident in human inspection. The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny

Stereogram – A type of hologram created from sequential images of a piece of movie footage. Each frame of the movie is converted into a vertical slit image and stacked against another slit image of the adjacent frame. The result is a hologram which, when the viewing angle changes from side to side, produces the same image motion as the movie footage, given that the frames are seen one after another.

Stock – The suspension of fibre and other materials in water used to manufacture paper.

Store of value – One of the functions of money or more generally of any asset that can be saved and exchanged at a later time without loss of its purchasing power. See also Precautionary holding.

Strap – A simple paper device designed to hold a specific denomination and number of banknotes. Can also refer to a bundle of banknotes.

Strike – The process of stamping a coin blank with a design. The stamping speed is measured in the number of strikes per minute.

Structured query language (SQL) – The standard language used to communicate with relational database management systems (ie. systems which store and provide access to data points that relate to one another). SQL statements are used to perform tasks such as updating and retrieving data.

Substrate – The material or base – eg. paper or film – on which an image is printed or a feature applied.

Super app – A mobile or web application that can provide multiple services including payment and financial transaction processing, effectively becoming an all-encompassing self-contained commerce and communication online platform that embraces many aspects of personal and commercial life.

Supply chain – Individuals or organisations involved in moving products from manufacturer to consumer.

Surface relief hologram – The most ubiquitous and popular type of hologram, mainly exhibiting a characteristic rainbow-coloured pattern. The details of the hologram image are recorded as an interference pattern on the surface (rather than through the volume) of the material. The value of surface relief holograms is that they can be mass-produced mechanically by embossing or casting a relief pattern or image into an inexpensive thermoplastic film or viscous coating on a film or paper.

Surface-applied feature – Security features that are applied to the surface of a banknote or secure document (eg. foil stripes, foil or optically variable ink patches, iridescent coatings) as opposed to features that are created through combinations of printing techniques or features integrated into the substrate, such as threads, fibres and watermarks.

Symbology – A protocol for arranging the bars and spaces of barcodes for the encoding of numbers, letters and binary numbers.

Synchrotron – A type of circular particle accelerator. It works by accelerating charged particles (electrons) through sequences of magnets until they reach almost the speed of light. These fast-moving electrons produce very bright light, called synchrotron light.

Tactile feature – The property of a banknote or secure document feature that can be felt, often made by means of intaglio printing.

Tactile mark for visually impaired – Marks printed in intaglio, recognisable by feel and usually located close to the edge of a banknote.

Taggant
Also known as
Forensic marker
– Molecular or microscopic particle that can be organic or inorganic in composition and exhibit specific and unique physical, biological, chemical or spectroscopic properties. Added in very low concentration to substrates or ink as a covert authentication feature.

Tamper-evident feature – A device such as a seal or closure that demonstrates that a product or packaging has been (fraudulently) opened or otherwise accessed prior to its proper use.

Tax stamp
Also known as
Excise label/tax banderole
– A label or tag applied to an item that denotes that tax or excise duty has been paid on the item.

Thermal dye sublimation – A technique often used on card printers, especially for printing photographs of faces. Consists of a dye carried on a ribbon which sublimes above a specific temperature (ie. changes from solid to gas without passing through a liquid phase). The dye then diffuses into the upper layers of the substrate after which it re-solidifies upon cooling.

Thermal printing – A process which produces a printed image by selectively heating coated thermochromic paper. The coating turns black in the areas where the paper is heated, producing an image.

Thermochromic ink – An ink that undergoes a reversible colour shift when heated and then cooled. The temperature change can be quite narrow so the viewer’s external body temperature, by applying, say, a thumb to the printed surface, is sufficient to trigger the transition.

Thermographic printing – A post-print technology for producing a tactile raised finish. Involves sprinkling powdered resin onto wet ink before heat-fusing it onto the substrate.

Thin-film deposition – A method of coating a very thin film of material – between a few nanometers to about 100 micrometres’ thickness – onto a substrate surface, or onto a previously deposited coating to form layers.

Thin-film interference – The superposition of two or more lightwaves, causing their mutual amplification or reduction depending on how the phases of these waves are related to each other.

Token – A representation of another object using a non-representative substitute. A sensitive data element, or valuable item, is represented with a non-sensitive equivalent, referred to as a token, with no extrinsic or exploitable meaning or value. The token acts as a reference (ie. identifier) that maps back to sensitive data through a tokenisation system.

Tokenisation – The transformation of the rights to an asset into digital form (token).

Tolerance – The amount by which a measurement or calculation might change and still be acceptable.

Tracing – The process of identifying the origin of an item or where it has been.

Track and trace
Also known as
Traceability
– The process of monitoring and recording the past and present whereabouts of an item, as it passes through different operators on its way to its destination.

Tracking – The process of following an item through the supply chain so its whereabouts are known at all times.

Transmission hologram – A hologram that can be seen by light passing through the material containing the holographic recording. Ironically, all metallised, embossed holograms are transmission holograms but are conveniently seen by reflected light because the incident light passes through the diffractive grating and is reflected back by the mirror coated on the reverse side.

Transmitted light – The passing of light through an object (as opposed to light reflecting off or absorbed by an object). Watermarks in security paper are usually viewed in transmitted light by holding the paper up to the light source.

Transparent window – A transparent area on a banknote incorporating optical effects by applying different elements, such as inkless embossing, liquid crystals or an optically variable device. Currently used both on polymer and paper banknotes.

Troy ounce – Anglo-Saxon weight unit, equivalent to 31.10 grammes. Used in the precious metals industry.

Trust service provider (TSP) – A person or legal entity providing and preserving digital certificates to create and validate electronic signatures and authenticate their signatories.The TSP has the responsibility to assure the integrity of electronic identification for signatories and services through strong mechanisms for authentication, electronic signatures and digital certificates.

Ultra-high frequency radio frequency identification (UHF RFID) – While RFID is a generic term encompassing different operating radio frequencies and standards, UHF is a frequency band covering 300MHz to 3GHz. UHF systems are known for generating long read ranges, up to 12m, whereas high frequency (HF) systems carry a much shorter read range, of approximately 1m. UHF allows for a faster data transfer rate, up to 20 times the range and speed of HF systems.

Ultraviolet curing (UV curing) – A photochemical process in which high-intensity ultraviolet light is used to instantly cure or ‘dry’ inks, coatings or adhesives.

Ultraviolet dull (UV dull) – A first-level requirement of security paper, which needs to be made from virgin pulp without optical brighteners (ie. which is UV-dull). This is because optical brighteners mask or interfere with UV fluorescent security print and fibres.

Ultraviolet light (UV light) – Electromagnetic waves located beyond the blue end of the visible light spectrum, commonly defined within the wavelength range of 100nm-400nm. UV light is often used to analyse secure documents and banknotes, and security features such as paper brightness, fluorescent inks and fluorescent fibres. UV lamps used in shops and banks to verify banknotes operate at a wavelength of 365nm.

Unbanked – People who do not have a bank account.

Uncirculated coin – A coin which has not been distributed or used as currency.

Underbanked – People who have a bank account but do not actively use it. For example, they may receive a government benefit payment into the account but they then withdraw it in cash and do not use the account further.

Unfit banknote – The opposite of a fit banknote. A banknote which, due to its deterioration or poor quality, is no longer suitable to be returned into circulation, and will be destroyed by the central bank.

Uniface coin – A coin, banknote, medal or token which has only been struck on one side.

Uniform resource locator (URL) – Colloquially termed ‘web address’. A reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it.

Unique identifier (UID/UI/UIM)
Also known as
Unique identification marking
– In the context of product traceability, a unique identifier is a serial number, assigned by a central authority for application to unit packages of products for the purpose of track and trace. No two serial numbers are the same, thereby allowing for the identification of individual retail-saleable items throughout the supply chain.

Unit packet
Also known as
Unit pack
– The smallest individual packaging of a tobacco product (one pack of cigarettes usually holds 20 individual sticks).

Universal access device (UAD) – Device designed to allow central bank digital currencies to be held and used offline. This could be a card or a specialised device.

Universal product code (UPC) – The first, and most common 1D (linear) barcode for retail product labelling, encoding global trade item numbers (GTINs) in line with GS1 international standards. UPCs are composed of 12 digits encoded in a series of vertical lines. The first six digits correspond to the manufacturer’s identiﬁcation number, the next ﬁve represent a speciﬁc product type and packaging conﬁguration, and the last one is a check digit.

Upconversion
Also known as
Anti-Stokes emission
– A material that absorbs energy at a longer wavelength outside the visible spectrum and emits in the visible spectrum. The materials that can achieve this effect are rare and therefore used for security marking.

Vacuum deposition
Also known as
Vacuum metallisation
– A process for creating a layer of metal on a substrate. Involves heating the metal target material until it vapourises inside a vacuum chamber. This allows the metal vapour to condensate and form a thin layer over the top of the substrate. Vacuum deposition is a common method of producing security threads.

Variable printing – The use of digital print processes to apply personalised and serialised information, such as unique identifiers and barcodes, to products and documents.

Varnishing – Applied to a banknote, this is the process by which the surface of the note is coated with a layer of varnish with the purpose of decreasing the level of absorption of the substrate, thereby reducing its soiling and prolonging the life of the note in circulation.

Vector graphic – Unlike raster images, a vector is not composed of separate dots (pixels). Vector graphics are composed of control points with curves in between them, defined by a mathematical formula. Vector graphics are often used for printing brochures etc., which do not require accurate transmission of all the shades of a particular colour and which can be described by curves. A great advantage of vector graphics is that the scaling of images does not affect their quality. One of the most popular vector graphics editors is Adobe Illustrator.

Verification – The process of verifying specific identity, document or product attributes, or determining the authenticity of credentials in order to give authorisation for a particular service.

Vignette – A small illustration on a banknote that fades into the background rather than being framed by a border.

Virtual reality (VR) – A technology that immerses the viewer in a computer-generated simulation of a 3D scene and allows them to interact with it using a digital interface. VR devices often use the term ‘hologram’ to describe the heightened sense of realism they provide.

Visa – A permission to enter the territory of a country. Can be in the form of a sticker with a multilevel security system, an insert, a stamp or a small sticker. A visa is placed on special pages of a travel document. There are machine-readable and non-machine-readable visas.

Viscose – The reformation of cellulose to give a textile fibre that may carry security features and be embedded into security paper.

Vishing
Also known as
Voice phishing
– The fraudulent practice of making phone calls or leaving voice messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as bank details and credit card numbers.

Visible digital seal (VDS) – A cryptographically signed data structure containing document features, encoded as a 2D barcode and printed on a document. The use of a VDS is recommended by ISO 22381:2018 as an open source, trusted entry point to allow all stakeholders to authenticate a unique identifier without having to go online, as well as access information on the security features used on a security document.

Visible light – Wavelengths within the visible spectrum of 380nm-740nm.

Void label – Tamper-evident labels that reveal a covert ‘void’ message when removal of the labels is attempted. Also refers to anticopy labels that, upon scanning, reveal the word ‘void’ in the copy.

Void pantograph – A method of making copy-evident and tamper-resistant patterns in the background of a document. Normally these are invisible to the naked eye, but become obvious when the document is photocopied. Typically, they spell out ‘void’, ‘copy’, or ‘invalid’. See also Big dot little dot.

Volume hologram
Also known as
Bragg diffraction hologram
– Refers to holograms where the thickness of the recording material is much larger than the wavelength of light used for recording. One of the most common types of hologram (together with surface relief holograms), volume holograms are mass-produced through optical copying of a master hologram onto photopolymer materials, so they retain more of the optical properties of the master than the mechanical, surface relief process. This allows them to be used for classical holograms which are fully 3D images, displaying depth and both vertical and horizontal parallax. Volume holograms are either monochromatic or two-colour, with a distinctly different appearance to rainbow holograms, which are based on diffraction.

Waffling – A means of defacing coins to render them worthless/unfit for circulation prior to being melted down or sold for scrap. The process takes its name from the pattern forced into the surface of coins under extreme pressure, which distorts it by creating a series of wavy lines similar to a waffle.

Watermark – An image in paper produced by varying the thickness and density of the paper mass during paper production. These variations form a discernible image that can be viewed when holding the paper up to the light. Used as a security feature on most banknotes.

Watermark – Fourdrinier or cylinder mould – A part of the production process of many security papers that uses pressure through a wire mesh to form designs or patterns by varying the thickness of the paper.

Watermark – digital – A type of marker directly embedded within video, audio or print content, which is imperceptible to humans but readable by computers.Typically used to identify ownership of copyright and authenticate a genuine article.

Watermark magnetics – A photonic watermark for banknotes, developed by combining a invisible photonic printing with a translucent and ultra-thin magnetic-responsive photonic display film.

Wavelength – A property of electromagnetic radiation that denotes the distance between waves of light.

Wavelet transform – A mathematical means for performing a signal analysis when signal frequency varies over time.

Wearable technology – A category of electronic devices that can be worn as accessories, embedded in clothing, implanted in the user’s body, or even tattooed on the skin.

Web – A continous roll of flexible material, usually paper, foil, film or laminate in a roll form.

Web printing process – Involves the feeding of a continuous roll (or web) of paper through the printing press. Web-fed offset lithography (as opposed to sheet-fed offset) is the predominant print process for tax stamps and other security labels.

Wet offset printing – An indirect lithographic printing process where a flat printing plate prints onto a rubber blanket that transfers the image onto the paper. The printing plate must be moistened with water before it is inked, with the water adhering to the non-image area.

Wet-glue application – The application of a coating of wet glue to a dry substrate before it is attached to an item. This is the main way of applying tax stamps to products.

Whizzing – The severe polishing of a coin in an attempt to improve its appearance and saleability to the uninformed.

WHO FCTC Protocol – World Health Organisation Framework Convention on Tobacco Control (WHO FCTC) global treaty, and its Protocol to Eliminate Illicit Trade in Tobacco Products. The Protocol requires all parties to implement secure track and trace systems by 2023.

Windowed thread – A paper-embedded security thread surfacing at regular intervals in a document and full visible when viewed in transmission.

Wire rim – A slight flange (protruded rim) on coins or medals caused by heavy striking pressure, often characteristic on proof coins.

Working die – A metal punch used to impress images into coins.

Zero knowledge proof – A method for proving that a statement is true without offering further information to the verifier, eg. confirming an ID without submitting passport or driving licence documents.

Zero order device (ZOD) – A device comprising gratings of less than the wavelength of visible light (ie. below 400nm). Can be produced by embossing and displays unique colour effects depending on the device’s plane of rotation.

Zero trust – Zero trust assumes there is no implicit trust granted to assets or user accounts based solely on their physical or network location (ie. local area networks versus the internet) or based on asset ownership (enterprise or personally owned).

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