Schematron (XML Schema)

A.8. Schematron

Table A-4. Schematron fact sheet

Author:	Rick Jelliffe and other contributors. Will be described by ISO/DSDL.
Status:	Unofficial.
Location:	http://www.ascc.net/xml/schematron.
Type:	Rule-based.
PSVI:	No.
Structures:	No (although the structure can be controlled by rules).
Datatypes:	No (although the datatypes can be controlled by rules).
Integrity:	No (although the integrity can be controlled by rules).
Rules:	Yes.
Vendor support:	Low but increasing.
Miscellaneous:	Pure rule expression. Can be embedded in W3C XML Schema and RELAX NG.

A.8.1. Example

<sch:schema xmlns:sch="http://www.ascc.net/xml/schematron">
  <sch:title>
    Schematron Schema for library
  </sch:title>
  <sch:pattern>
    <sch:rule context="/">
      <sch:assert test="library">
        The document element should be "library".
      </sch:assert>
    </sch:rule>
    <sch:rule context="/library">
      <sch:assert test="book">
        There should be at least a book!
      </sch:assert>
      <sch:assert test="not(@*)">
        No attribute for library, please!
      </sch:assert>
    </sch:rule>
    <sch:rule context="/library/book">
      <sch:assert test="not(following-sibling::book/@id=@id)">
        Duplicated ID for this book.
      </sch:assert>
      <sch:assert test="@id=concat('-', isbn)">
        The id should be derived from the ISBN.
      </sch:assert>
    </sch:rule>
    <sch:rule context="/library/*"> 
      <sch:assert test="name()='book' or name( )='author' or
        name( )='character'">
        This element shouldn't be here...
      </sch:assert>
    </sch:rule>
  </sch:pattern>
</sch:schema>

Note that the previous Schematron is a partial schema meant as a supplement.