---
title: uniqueIdentifier
description: Unique identifier for a directory object. The semantics of uniqueness are defined locally for the directory, so the values are not necessarily universally unique identifiers, but might be a payroll number for an individual or a department code for an organizational unit.
component: pingds
version: 8.1
page_id: pingds:schemaref:at-uniqueIdentifier
canonical_url: https://docs.pingidentity.com/pingds/8.1/schemaref/at-uniqueIdentifier.html
---

# uniqueIdentifier

Unique identifier for a directory object. The semantics of uniqueness are defined locally for the directory, so the values are not necessarily universally unique identifiers, but might be a payroll number for an individual or a department code for an organizational unit.

|                             |                                                                |
| --------------------------- | -------------------------------------------------------------- |
| *OID*                       | 0.9.2342.19200300.100.1.44                                     |
| *Names*                     | uniqueIdentifier                                               |
| *Syntax*                    | [DirectoryString](s-DirectoryString.html)                      |
| *Equality matching rule*    | [caseIgnoreMatch](mr-caseIgnoreMatch.html)                     |
| *Ordering matching rule*    | [caseIgnoreOrderingMatch](mr-caseIgnoreOrderingMatch.html)     |
| *Substring matching rule*   | [caseIgnoreSubstringsMatch](mr-caseIgnoreSubstringsMatch.html) |
| *Single value*              | false: multiple values allowed                                 |
| *User modification allowed* | true                                                           |
| *Usage*                     | userApplications                                               |
| *Origin*                    | [RFC 4524](https://datatracker.ietf.org/doc/html/rfc4524)      |
| *Schema file*               | 00-core.ldif                                                   |
| *Used by*                   | [pilotObject](oc-pilotObject.html)                             |