# Glossary - De-Identification Handbook v2.0.0-comment

* [**Table of Contents**](toc.md)
* **Glossary**

## Glossary

**anonymization**: process by which personal data is irreversibly altered in such a way that a data subject can no longer be identified directly or indirectly, either by the data controller alone or in collaboration with any other party (Source: [(ISO 25237, 2017)](references.md#ISO25237).

**Note 1:** The term is defined in a similar way under the PIPL ([Art. 73(4)](http://en.npc.gov.cn.cdurl.cn/2021-12/29/c_694559_3.htm)).

**Note 2:** An absolute concept of anonymization is not feasible in practice. This book interprets it as a relative concept, where the risk of re-identification, even with reasonable additional information, is minimized to a very low level.

**anonymous identifier**: identifier of a person which does not allow the identification of the natural person(Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**data linking**: matching and combining data from multiple databases (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1**: The term "data linking" is identical to the term "linking" defined in the [(ISO/IEC 20889, 2018)](references.md#ISO20889).

**data subject**: person to whom data refer (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1**: The term "data subject" is identical to the term "data principal" defined in the [(ISO/IEC 20889, 2018)](references.md#ISO20889).

**de-identification**: general term for any process of reducing the association between a set of identifying data and the data subject. (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1:** The term "de-identification" is distinguished from the term "anonymization" under the PIPL[(PIPL, 2021)](references.md#PIPL2021). De-identification under the PIPL is similar to the concept of pseudonymization in this book.

**Note 2:** The term "de-identification" in this handbook is identical to the definition of "de-identification process" within the [(ISO/IEC 20889, 2018)](references.md#ISO20889).

**direct identifier**: data that directly identifies a single individual. (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1:** Direct identifiers are those data that can be used to identify a person without additional information or with cross-linking through other information that is in the public domain.

**Note 2:** The term “directly identifying data” in [(ISO 20237,2017)](references.md#ISO25237) has been simplified according to [(ISO/IEC 20889, 2018)](references.md#ISO20889).

**identifiable natural person**: one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person. (Source: [GDPR Art 4(1)](https://gdpr-info.eu/art-4-gdpr/)).

**Note 1:** Similar to the concept of identifiable person within [(ISO 25237, 2017)](references.md#ISO25237).

**imputed value**: plausible substitutes generated by applying statistical methods to replace sensitive, missing, or identifying data points, preserving data utility and privacy.

**indirect identifier**: data that can identify a single person only when used together with other indirectly identifying data. (Source: [(ISO 25237, 2017)](references.md#ISO25237)), modified).

**Note 1:** Indirect identifiers can reduce the population to which the person belongs, possibly down to one if used in combination.

**Note 2:** The term "indirectly identifying data" in [(ISO 25237, 2017)](references.md#ISO25237) has been simplified according to [(ISO/IEC 20889, 2018)](references.md#ISO20889).

**Note 3:** The term "indirect identifier" in this handbook is identical to the definitions of "indirect identifier" and "quasi-identifier".

**Example** Postcode, sex, age, date of birth.

**irreversibility**: situation when, for any passage from identifiable to pseudonymous, it is computationally unfeasible to trace back to the original identifier from the pseudonym (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**linkability**: property for a dataset that it is possible to associate (by linking) a record concerning a data subject with a record concerning the same data subject in a separate dataset. (Source: [(ISO/IEC 20889, 2018)](references.md#ISO20889)).

**microdata**: dataset comprised of records related to individual data principals (Source: [(ISO/IEC 20889, 2018)](references.md#ISO20889)).

**natural person**: real human being as opposed to a legal person which may be a private or public organization (Source:[(ISO 25237, 2017)](references.md#ISO25237)).

**personal identifier**: information with the purpose of uniquely identifying a person within a given context (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1:** Personal identifier can be used to directly identify a person, therefore is also directly identifying data.

**pseudonym**: personal identifier that is different from the normally used personal identifier and is used with pseudonymized data to provide dataset coherence linking all the information about a subject, without disclosing the real world person identity (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1:** This may be either derived from the normally used personal identifier in a reversible or irreversible way or be totally unrelated.

**Note 2:** Pseudonym is usually restricted to mean an identifier that does not allow the direct derivation of the normal personal identifier. Such pseudonymous information is thus functionally anonymous. A trusted third party may be able to obtain the normal personal identifier from the pseudonym.

**pseudonymization**: particular type of de-identification that both removes the association with a data subject and adds an association between a particular set of characteristics relating to the data subject and one or more pseudonyms. (Source: [(ISO 25237, 2017)](references.md#ISO25237)).

**Note 1:** This includes irreversible and reversible pseudonymization which is similar to the concept of pseudonymization under the GDPR.

**Note 2:** The pseudonymized data can no longer be attributed to a specific data subject without the use of additional information, but could be attributed to a natural person by the use of additional information (Source: [GDPR Recital 26](https://www.privacy-regulation.eu/en/recital-26-GDPR.htm)).

**Note 3:** The term defined in the handbook is different from the definition specified in the [(ISO/IEC 20889, 2018)](references.md#ISO20889) where "pseudonymization" refers to a type of de-identification technique.

**re-identification**: process of associating data in a de-identified dataset with the original data subject (Source: [(ISO/IEC 20889, 2018)](references.md#ISO20889)).

**Note 1:** A process that establishes the presence of a particular data subject in a dataset is included in this definition.

**re-identification attack**: action performed on de-identified data by an attacker with the purpose of re-identification (Source: [(ISO/IEC 20889, 2018)](references.md#ISO20889)).

**re-identification risk**: risk of a successful re-identification attack (Source: [(ISO/IEC 20889, 2018)](references.md#ISO20889)).

