1<schema xmlns="http://www.ascc.net/xml/schematron" >
2     <pattern name="Open model">
3          <rule context="AAA">
4               <assert test="BBB"> BBB element is not present</assert>
5               <assert test="CCC"> CCC element is not present</assert>
6          </rule>
7     </pattern>
8     <pattern name="Closed model">
9          <rule context="AAA">
10               <assert test="BBB"> BBB element is not present</assert>
11               <assert test="CCC"> CCC element is not present</assert>
12               <assert test="count(BBB|CCC) = count (*)">There is an extra element</assert>
13          </rule>
14     </pattern>
15</schema>
16