1<schema xmlns="http://www.ascc.net/xml/schematron" > 2 <pattern name="Attributes present"> 3 <rule context="BBB"> 4 <assert test="not(@aaa) or (@aaa and @bbb)">The element must not have an isolated aaa attribute</assert> 5 <assert test="not(@bbb) or (@aaa and @bbb)">The element must not have an isolated bbb attribute</assert> 6 </rule> 7 </pattern> 8</schema> 9