XML Schema and RDF Schema specification, containing sets of modules which frame and embed contextual human characteristics including physical, cultural, social, kinesic, psychological, and intentional features within conveyed information.

XML Schema is used to express shared vocabularies and allow machines to carry out rules made by people....

Schematron is a language and toolkit for making assertions about patterns found in XML documents...

What they are, how they work, and why you should use them.

 Looks at the differences between the two validation methods.

Top thinkers in web services are moving away from strongly typed models of data into a more document-centric service oriented model. Rich Salz charts this change in thinking

Those who deal with data transfer or document exchange within or across organizations with heterogeneous platforms will certainly accept and appreciate the need and power of XML. I am not going to delve into the merits of XML. I will, however, address a simple but powerful schema concept called XSD or XML Schema Definition

A comprehensive introduction to XML Schema, a W3C XML language for describing and constraining the content of XML documents. Includes quick reference tables.

RELAX NG XML Schema Language Published as an ISO Standard (DSDL Part 2).