What is an identity (Identität) according to eCH-0219?

An identity comprises properties of a subject or object; it is a data record that represents the subject or object unambiguously within a namespace, consisting of an identifier usually together with a set of further attributes.

A subject's identity arises at registration, which may include identification. The standard's homely example: an identity can be a row in an Excel or database table. A subject can have several identities, each with several digital identities, and usually one identity per domain.

Go deeper:

• Pfitzmann and Hansen, A terminology for talking about privacy by data minimization (PDF) — the classic terminology paper for identity, partial identity and pseudonymity.