This glossary is included to assist the reader with terms that may appear within articles in the ICAO MRTD Report magazine. It is not intended to be authoritative or definitive.

Anti-scan pattern An image usually constructed of fine lines at varying angular displacement and embedded in the security background design. When viewed normally, the image cannot be distinguished from the remainder of the background security print, but when the original is scanned or photocopied the embedded image becomes visible.
Biographical data (biodata) The personalized details of the bearer of the document appearing as text in the visual and machine readable zones on the biographical data page of a passport book, or on a travel card or visa.
Biometric A measurable, physical characteristic or personal behavioural trait used to recognize the identity, or verify the claimed identity, of an enrollee.
Biometric data The information extracted from the biometric sample and used either to build a reference template (template data) or to compare against a previously created reference template (comparison data).
Biometric sample Raw data captured as a discrete unambiguous, unique and linguistically neutral value representing a biometric characteristic of an enrollee as captured by a biometric system (for example, biometric samples can include the image of a fingerprint as well as its derivative for authentication purposes).
Biometric system An automated system capable of: 1. capturing a biometric sample from an end user for a MRP; 2. extracting biometric data from that biometric sample; 3. comparing that specific biometric data value(s) with that contained in one or more reference templates; 4. deciding how well the data match, i.e. executing a rule-based matching process specific to the requirements of the unambiguous identification and person authentication of the enrollee with respect to the transaction involved; and 5. indicating whether or not an identification or verification of identity has been achieved.
Black-line/white-line design A design made up of fine lines often in the form of a guilloche pattern and sometimes used as a border to a security document. The pattern migrates from a positive to a negative image as it progresses across the page.
Capture The method of taking a biometric sample from the end user.
Certificating authority A body that issues a biometric document and certifies that the data stored on the document are genuine in a way which will enable detection of fraudulent alteration.
Chemical sensitizers Security reagents to guard against attempts at tampering by chemical erasure, such that irreversible colours develop when bleach and solvents come into contact with the document.
Comparison The process of comparing a biometric sample with a previously stored reference template or templates. See also “One-to-many” and “One-to-one."
Contactless integrated circuit An electronic microchip coupled to an aerial (antenna) which allows data to be communicated between the chip and an encoding/reading device without the need for a direct electrical connection.
Counterfeit An unauthorized copy or reproduction of a genuine security document made by whatever means.
Database Any storage of biometric templates and related end user information.
Data storage (Storage) A means of storing data on a document such as a MRP. Doc. 9303, Part 1, Volume 2 specifies that the data storage on an ePassport will be on a contactless integrated circuit.
Digital signature A method of securing and validating information by electronic means.
Document blanks A document blank is a travel document that does not contain the biographical data and personalized details of a document holder. Typically, document blanks are the base stock from which personalized travel documents are created.
Duplex design A design made up of an interlocking pattern of small irregular shapes, printed in two or more colours and requiring very close register printing in order to preserve the integrity of the image.
Embedded image An image or information encoded or concealed within a primary visual image.
End user A person who interacts with a biometric system to enroll or have their identity checked.
Enrollment The process of collecting biometric samples from a person and the subsequent preparation and storage of biometric reference templates representing that person’s identity.
Enrollee A human being, i.e. natural person, assigned an MRTD by an issuing State or organization.
ePassport A Machine Readable Passport (MRP) containing a contactless integrated circuit (IC) chip within which is stored data from the MRP data page, a biometric measure of the passport holder and a security object to protect the data with Public Key Infrastructure (PKI) cryptographic technology, and which conforms to the specifications of Doc. 9303, Part 1.
Extraction The process of converting a captured biometric sample into biometric data so that it can be compared to a reference template.
Failure to acquire The failure of a biometric system to obtain the necessary biometric to enroll a person.
Failure to enroll The failure of a biometric system to enroll a person.
False acceptance When a biometric system incorrectly identifies an individual or incorrectly verifies an impostor against a claimed identity.
False Acceptance Rate (FAR) The probability that a biometric system will incorrectly identify an individual or will fail to reject an impostor. The rate given normally assumes passive impostor attempts. The false acceptance rate may be estimated as FAR = NFA / NIIA or FAR = NFA / NIVA where FAR is the false acceptance rate, NFA is the number of false acceptances, NIIA is the number of impostor identification attempts, and NIVA is the number of impostor verification attempts.
False match rate Alternative to “false acceptance rate;” used to avoid confusion in applications that reject the claimant if their biometric data matches that of an enrollee. In such applications, the concepts of acceptance and rejection are reversed, thus reversing the meaning of “false acceptance” and “false rejection.”
False non-match rate Alternative to “false rejection rate;” used to avoid confusion in applications that reject the claimant if their biometric data matches that of an enrollee. In such applications, the concepts of acceptance and rejection are reversed, thus reversing the meaning of “false acceptance” and “false rejection.”
False rejection When a biometric system fails to identify an enrollee or fails to verify the legitimate claimed identity of an enrollee.
False Rejection Rate (FRR) The probability that a biometric system will fail to identify an enrollee or verify the legitimate claimed identity of an enrollee. The false rejection rate may be estimated as follows: FRR = NFR / NEIA or FRR = NFR / NEVA where FRR is the false rejection rate, NFR is the number of false rejections, NEIA is the number of enrollee identification attempts, and NEVA is the number of enrollee verification attempts. This estimate assumes that the enrollee identification/verification attempts are representative of those for the whole population of enrollees. The false rejection rate normally excludes “failure to acquire” errors.
Fibres Small, thread-like particles embedded in a substrate during manufacture.
Fluorescent ink Ink containing material that glows when exposed to light at a specific wavelength (usually UV) and that, unlike phosphorescent material, ceases to glow immediately after the illuminating light source has been extinguished.
Forgery Fraudulent alteration of any part of the genuine document, e.g. changes to the biographical data or the portrait.
Front-to-back (see-through) register A design printed on both sides of the document or an inner page of the document which, when the page is viewed by transmitted light, forms an interlocking image.
Full frontal (facial) image A portrait of the holder of the MRP produced in accordance with the specifications established in Doc. 9303, Part 1, Volume 1, Section IV, 7.
Gallery The database of biometric templates of persons previously enrolled, which may be searched to find a probe.
Global interoperability The capability of inspection systems (either manual or automated) in different States throughout the world to obtain and exchange data, to process data received from systems in other States, and to utilize that data in inspection operations in their respective States. Global interoperability is a major objective of the standardized specifications for placement of both eye readable and machine readable data in all ePassports.
Guilloche design A pattern of continuous fine lines, usually computer generated, and forming a unique image that can only be accurately re-originated by access to the equipment, software and parameters used in creating the original design.
Heat-sealed laminate A laminate designed to be bonded to the biographical data page of a passport book, or to a travel card or visa, by the application of heat and pressure.
Holder A person possessing an ePassport, submitting a biometric sample for verification or identification while claiming a legitimate or false identity. A person who interacts with a biometric system to enroll or have their identity checked.
Identifier A unique data string used as a key in the biometric system to name a person’s identity and its associated attributes. An example of an identifier would be a passport number.
Identity The collective set of distinct personal and physical features, data and qualities that enable a person to be definitively identified from others. In a biometric system, identity is typically established when the person is registered in the system through the use of so-called “breeder documents” such as birth certificate and citizenship certificate.
Identification/Identify The one-to-many process of comparing a submitted biometric sample against all of the biometric reference templates on file to determine whether it matches any of the templates and, if so, the identity of the ePassport holder whose template was matched. The biometric system using the one-to-many approach is seeking to find an identity amongst a database rather than verify a claimed identity. Contrast with “Verification."
Image A representation of a biometric as typically captured via a video, camera or scanning device. For biometric purposes this is stored in digital form.
Impostor A person who applies for and obtains a document by assuming a false name and identity, or a person who alters his physical appearance to represent himself as another person for the purpose of using that person’s document.
Infrared drop-out ink An ink which forms a visible image when illuminated with light in the visible part of the spectrum and which cannot be detected in the infrared region.
Inspection The act of a State examining an ePassport presented to it by a traveler (the ePassport holder) and verifying its authenticity.
Intaglio A printing process used in the production of security documents in which high printing pressure and special inks are used to create a relief image with tactile feel on the surface of the document.
Issuing State The country writing the biometric to enable a receiving State (which could also be itself) to verify it.
JPEG and JPEG 2000 Standards for the data compression of images, used particularly in the storage of facial images.
Laminate A clear material, which may have security features such as optically variable properties, designed to be securely bonded to the biographical data or other page of the document.
Laser engraving A process whereby images (usually personalized images) are created by “burning” them into the substrate with a laser. The images may consist of both text, portraits and other security features and are of machine readable quality.
Laser-perforation A process whereby images (usually personalized images) are created by perforating the substrate with a laser. The images may consist of both text and portrait images and appear as positive images when viewed in reflected light and as negative images when viewed in transmitted light.
Latent image A hidden image formed within a relief image which is composed of line structures which vary in direction and profile resulting in the hidden image appearing at predetermined viewing angles, most commonly achieved by intaglio printing.
LDS The Logical Data Structure describing how biometric data is to be written to and formatted in ePassports.
Live capture The process of capturing a biometric sample by an interaction between an ePassport holder and a biometric system.
Machine-verifiable biometric feature A unique physical personal identification feature (e.g. an iris pattern, fingerprint or facial characteristics) stored on a travel document in a form that can be read and verified by machine.
Match/Matching The process of comparing a biometric sample against a previously stored template and scoring the level of similarity. A decision to accept or reject is then based upon whether this score exceeds the given threshold.
Metallic ink Ink exhibiting a metallic-like appearance.
Metameric inks A pair of inks formulated to appear to be the same colour when viewed under specified conditions, normally daylight illumination, but which are a mismatch at other wavelengths.
Microprinted text Very small text printed in positive and or negative form, which can only be read with the aid of a magnifying glass.
MRTD Machine Readable Travel Document, e.g. passport, visa or official document of identity accepted for travel purposes.
Multiple biometric The use of more than one biometric.
One-to-a-few A hybrid of one-to-many identification and one-to-one verification. Typically the one-to-a-few process involves comparing a submitted biometric sample against a small number of biometric reference templates on file. It is commonly referred to when matching against a “watch list” of persons who warrant detailed identity investigation or are known criminals, terrorists, etc.
One-to-many Synonym for “Identification.”
One-to-one Synonym for “Verification.”
Operating system A programme which manages the various application programmes used by a computer.
Optically Variable Feature (OVF) An image or feature whose appearance in colour and/or design changes dependent upon the angle of viewing or illumination. Examples are. features including diffraction structures with high resolution (Diffractive Optically Variable Image Device (DOVID), holograms, colour-shifting inks (e.g. ink with optically variable properties) and other diffractive or reflective materials.
Optional data capacity expansion technologies Data storage devices (e.g. integrated circuit chips) that may be added to a travel document to increase the amount of machine readable data stored in the document. See Doc. 9303, Part 1, Volume 2, for guidance on the use of these technologies.
Overlay An ultra-thin film or protective coating that may be applied to the surface of a biographical data or other page of a document in place of a laminate.
Penetrating numbering ink Ink containing a component that penetrates deep into a substrate.
Personalization The process by which the portrait, signature and biographical data are applied to the document.
Phosphorescent ink Ink containing a pigment that glows when exposed to light of a specific wavelength, the reactive glow remaining visible and then decaying after the light source is removed.
Photochromic ink An ink that undergoes a reversible colour change when exposed to UV light.
Photo substitution A type of forgery in which the portrait in a document is substituted for a different one after the document has been issued.
Physical security The range of security measures applied within the production environment to prevent theft and unauthorized access to the process.
PKI The Public Key Infrastructure methodology of enabling detection as to whether data in an ePassport has been tampered with.
Planchettes Small visible (fluorescent) or invisible fluorescent platelets incorporated into a document material at the time of its manufacture.
Probe The biometric template of the enrollee whose identity is sought to be established.
Rainbow (split-duct) printing A technique whereby two or more colours of ink are printed simultaneously by the same unit on a press to create a controlled merging of the colours similar to the effect seen in a rainbow.
Random access A means of storing data whereby specific items of data can be retrieved without the need to sequence through all the stored data.
Reactive inks Inks that contain security reagents to guard against attempts at tampering by chemical erasure (deletion), such that a detectable reaction occurs when bleach and solvents come into contact with the document.
Read range The maximum practical distance between the contactless IC with its antenna and the reading device.
Relief (3-D) design (Medallion) A security background design incorporating an image generated in such a way as to create the illusion that it is embossed or debossed on the substrate surface.
Receiving State The country reading the biometric and wanting to verify it.
Registration The process of making a person’s identity known to a biometric system, associating a unique identifier with that identity, and collecting and recording the person’s relevant attributes into the system.
Score A number on a scale from low to high, measuring the success that a biometric probe record (the person being searched for) matches a particular gallery record (a person previously enrolled).
Secondary image A repeat image of the holder’s portrait reproduced elsewhere in the document by whatever means.
Security thread A thin strip of plastic or other material embedded or partially embedded in the substrate during the paper manufacturing process. The strip may be metallized or partially de-metallized.
Tactile feature A surface feature giving a distinctive “feel” to the document.
Tagged ink Inks containing compounds that are not naturally occurring substances and which can be detected using special equipment.
Template/Reference template Data which represent the biometric measurement of an enrollee used by a biometric system for comparison against subsequently submitted biometric samples.
Template size The amount of computer memory taken up by the biometric data.
Thermochromic ink An ink which undergoes a reversible colour change when the printed image is exposed to heat (e.g. body heat).
Threshold A “benchmark” score above which the match between the stored biometric and the person is considered acceptable or below which it is considered unacceptable.
Token image A portrait of the holder of the MRP, typically a full frontal image, which has been adjusted in size to ensure a fixed distance between the eyes. It may also have been slightly rotated to ensure that an imaginary horizontal line drawn between the centers of the eyes is parallel to the top edge of the portrait rectangle if this has not been achieved when the original portrait was taken or captured (see Section 2, 13 in this volume of Doc. 9303, Part 1).
UV Ultraviolet light.
UV dull substrate A substrate that exhibits no visibly detectable fluorescence when illuminated with UV light.
Validation The process of demonstrating that the system under consideration meets in all respects the specification of that system.
Variable laser image A feature generated by laser engraving or laser perforation displaying changing information or images dependent upon the viewing angle.
Verification/Verify The process of comparing a submitted biometric sample against the biometric reference template of a single enrollee whose identity is being claimed, to determine whether it matches the enrollee’s template. Contrast with “Identification”.
Watermark A custom design, typically containing tonal gradation, formed in the paper or other substrate during its manufacture, created by the displacement of materials therein, and traditionally viewable by transmitted light.
Wavelet Scalar Quantization A means of compressing data used particularly in relation to the storage of fingerprint images.