<sch:rule context="@data">
<sch:assert role="warning" test="not(normalize-space(.) eq '')">@data attribute should
have content.</sch:assert>
<sch:assert role="warning" test="every $i in tokenize(., '\s+') satisfies substring($i,2)=//mei:*[ancestor::mei:music]/@xml:id">The value in @data should correspond to the @xml:id attribute of a descendant of
the music element.</sch:assert>
</sch:rule>
<classSpec ident="att.dataPointing" module="MEI.shared" type="atts">
<desc>Attributes for linking metadata to data.</desc>
<attList org="group">
<attDef ident="data" usage="opt">
<desc>Used to link metadata elements to one or more data-containing elements.</desc>
<constraintSpec ident="check_dataTarget" scheme="isoschematron">
<constraint>
<sch:rule context="@data">
<sch:assert role="warning" test="not(normalize-space(.) eq '')">@data attribute should
have content.</sch:assert>
<sch:assert role="warning" test="every $i in tokenize(., '\s+') satisfies substring($i,2)=//mei:*[ancestor::mei:music]/@xml:id">The value in @data should correspond to the @xml:id attribute of a descendant of
the music element.</sch:assert>
</sch:rule>
</constraint>
</constraintSpec>
</attDef>
</attList>
</classSpec>