<sch:rule context="mei:*[@origin.tstamp2]">
<sch:assert test="@origin.tstamp">When @origin.tstamp2 is used @origin.tstamp must
also be present.</sch:assert>
</sch:rule>
<classSpec ident="att.origin.timestamp.logical" module="MEI.shared" type="atts">
<desc>Attributes that identify a musical range in terms of musical time.</desc>
<attList org="group">
<attDef ident="origin.tstamp" usage="opt">
<desc>encodes the starting point of musical material in terms of musical time, i.e., a
(potentially negative) count of measures plus a beat location.</desc>
</attDef>
<attDef ident="origin.tstamp2" usage="rec">
<desc>encodes the ending point of musical material in terms of musical time, i.e., a count
of measures plus a beat location. The values are relative to the measure identified
by
<att scheme="TEI">origin.tstamp</att>.</desc>
<constraintSpec ident="origin.tstamp2_requires_origin.tstamp" scheme="isoschematron">
<constraint>
<sch:rule context="mei:*[@origin.tstamp2]">
<sch:assert test="@origin.tstamp">When @origin.tstamp2 is used @origin.tstamp must
also be present.</sch:assert>
</sch:rule>
</constraint>
</constraintSpec>
</attDef>
</attList>
</classSpec>