ISO/IEC 19757-5:2011 Preview
Information technology -- Document Schema Definition Languages (DSDL) -- Part 5: Extensible Datatypes
This standard was last reviewed and confirmed* in 2016.
*Therefore this version remains current
ISO/IEC 19757-5:2011 specifies an XML language that allows users to create and extend datatype libraries for their own purposes. The datatype definitions in these libraries can be used by XML validators and other tools to validate content and make comparisons between values.