PUBLIC MARKS from fredbird with tag relaxng

RELAX NG is a simple schema language for XML, based on [RELAX] and [TREX]. A RELAX NG schema specifies a pattern for the structure and content of an XML document. A RELAX NG schema thus identifies a class of XML documents consisting of those documents that match the pattern. Two syntaxes have been defined for RELAX NG. The original syntax uses XML; with this syntax an RELAX NG schema is itself an XML document. Subsequently, a compact non-XML syntax has been defined. This document is a tutorial for RELAX NG version 1.0 using the XML syntax.