* W3C XML Schemas Part 2: Datatypes [REC 02 May 2001](https://www.w3.org/TR/2001/REC-xmlschema-2-20010502/)
* W3C XML Schemas 1.0 Part 2: Datatypes [REC 02 May 2001](https://www.w3.org/TR/2001/REC-xmlschema-2-20010502/)
* W3C [xml:id](https://www.w3.org/TR/xml-id/) Working Draft 7 April 2004
In most cases libxml2 tries to implement the specifications in a relatively strictly compliant way. As of release 2.4.16, libxml2 passed all 1800+ tests from the [OASIS XML Tests Suite](https://www.oasis-open.org/committees/xml-conformance/).