A Schematron schema for songs

• A schema contains a title and a pattern

• Each pattern contains rule child elements

• Each rule contains assert and report elements and has a context attribute

• Each assert and report element has a test attribute containing an XPath expression whihc returns a boolean.

• The contents of each assert element is printed if the assertion test fails

• The contents of each report element is printed if the report test succeeds

<?xml version="1.0"?>
<schema xmlns="http://www.ascc.net/xml/schematron">
  <title>A Schematron Schema for Songs</title>
  <pattern>
    <rule context="SONG">
      <assert test="TITLE">
        A SONG must contain an initial TITLE element.
      </assert>
      <assert test="TITLE[position()=1]">
        The TITLE element must be the initial element of the SONG element.
      </assert>
      <assert test="COMPOSER">
        A SONG must contain at least one COMPOSER element.
      </assert>
      <assert test="ARTIST">
        A SONG must contain at least one ARTIST element.
      </assert>
    </rule>
  </pattern>
</schema>