An overview of the architecture, with a view to producing customised versions is also provided.This paper provides an introduction to Schematron; an innovative XML validation language developed by Rick Jelliffe.The Schematron language is then discussed, covering all major elements in the language with examples of their usage.
As the XPath specification [XPath] shows, there are many possible kinds of relationship, known as 'axes'.
During the last few years a number of different XML schema languages have appeared as suggested replacements for the ageing Document Type Definition (DTD).
The majority of these have taken the basic premise of recasting DTD functionality in XML syntax with the addition, in some cases, of other features such as data typing, inheritance, etc [XMLSchema].
Assertions are therefore the mechanism for placing constraints on the relationships between nodes in a graph (elements and attributes in an XML document).
For example, we may select all Regular grammars, as used in DTDs, can then be viewed as tree patterns where the only available axis is the parent-child axis [Jelliffe1999e].Full use of tree pattern validation provides the maximum amount of freedom when modelling constraints for a schema.