What is ISO/IEC 19757-3 about?
A document model is an expression of the constraints to be placed on the structure and content of documents to be validated with the model. A number of technologies have been developed through various formal and informal consortia since the development of Document Type Definitions (DTDs) as part of ISO 8879 , notably by the World Wide Web Consortium (W3C) and the Organization for the Advancement of Structured Information Standards (OASIS).
ISO/IEC 19757-3 brings together different validation-related tasks and expressions to form a single extensible framework that allows technologies to work in series or in parallel to produce a single or a set of validation results.
ISO/IEC 19757-3 discusses Document Schema Definition Languages (DSDL) with a focus on Schematron, a schema language for Extensible Markup Language (XML).