[tei-council] schematron test on <app> causes false? positive

[Sebastian Rahtz]

we say on <app> that

   <constraint xmlns:sch="http://purl.oclc.org/dsdl/schematron">
      <sch:assert test="count( descendant::tei:lem[ generate-id(    current() ) = generate-id(    ancestor::tei:app[1] ) ]) &lt;       2">
Only one &lt;lem&gt; element may appear within a single  apparatus
entry, whether it appears outside a &lt;rdgGrp&gt;
element or within it.</sch:assert>
    </constraint>

but this example in the Guidelines

<egXML xmlns="http://www.tei-c.org/ns/Examples">
                    <app type="substantive">
                      <rdgGrp type="subvariants">
                        <lem wit="#El #Hg">Experience</lem>
                        <rdg wit="#Ha4">Experiens</rdg>
                      </rdgGrp>
                      <rdgGrp type="subvariants">
                        <lem wit="#Cp #Ld1">Experiment</lem>
                        <rdg wit="#La">Ex<g ref="#per"/>iment</rdg>
                      </rdgGrp>
                      <rdgGrp type="subvariants">
                        <lem>Eriment<wit>[unattested]</wit>
                        </lem>
                        <rdg wit="#Ra2">Eryment</rdg>
                      </rdgGrp>
                    </app>

fails that test. Would someone who groks this like to consider whether the example is wrong, or the 
Schematron test incomplete?
--
Sebastian Rahtz      
Director (Research) of Academic IT
University of Oxford IT Services
13 Banbury Road, Oxford OX2 6NN. Phone +44 1865 283431