RELAX NG

Using External References

External references offer a powerful but simple mechanism for including a pattern contained in an external document at any location in a schema. This feature works through raw inclusion of the referenced external document. The externalRef pattern is replaced by the content of the document. That document may be a complete RELAX NG schema, though that isn’t required, but a valid pattern is required.

With Russian Doll Schemas

You may want to reuse existing schemas as a whole, without modifying any of their definitions. Imagine, for instance, that we have defined two grammars in two schemas to describe our author and character elements. First, create a RELAX NG schema, author.rng, to describe our authors:

 <?xml version="1.0" encoding="UTF-8"?>
 <element name="author" xmlns="http://relaxng.org/ns/structure/1.0" 
   datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
   <attribute name="id">
     <data type="ID"/>
   </attribute>
   <element name="name">
     <data type="token" datatypeLibrary=""/>
   </element>
   <optional>
     <element name="born">
       <data type="date"/>
     </element>
   </optional>
   <optional>
     <element name="died">
       <data type="date"/>
     </element>
   </optional>
 </element>

or, in the compact syntax, author.rnc:

 element author {
   attribute id { xsd:ID },
   element name { token },
   element born { xsd:date }?,
   element died { xsd:date }?
 }

Then create a second schema, character.rng, to describe our characters:

 <?xml version="1.0" encoding="UTF-8"?> <element name="character" xmlns="http://relaxng.org/ns/structure/1.0" ...