1<schema xmlns="http://www.ascc.net/xml/schematron" >
2     <pattern name="Number of characters in an abbreviation">
3          <rule context="BBB">
4               <report test="string-length(@bbb) &lt; 2">There is not enough letters in the abbreviation</report>
5               <report test="string-length(@bbb) > 3">There is too much letters in the abbreviation</report>
6          </rule>
7     </pattern>
8</schema>
9