1 <?xml version="1.0"?> 2 <schema xmlns="http://purl.oclc.org/dsdl/schematron"> 3 <title>Test of Schematron validation</title> 4 <pattern> 5 <rule context="zoo"> 6 <assert test="cage[@id]">A zoo contains cages each with an id attribute</assert> 7 </rule> 8 </pattern> 9 </schema>