The starting point of the mordent may be indicated by either a @startid, @tstamp, @tstamp.ges, or @tstamp.real attribute. It is a semantic error not to specify one of these attributes.
<elementSpec rend="add" ident="mordent" module="MEI.cmnOrnaments"><desc xml:lang="en">An ornament indicating rapid alternation of the main note with a secondary note, usually
a
step below, but sometimes a step above.
</desc>
<classes>
<memberOf key="att.common"/>
<memberOf key="att.mordent.log"/>
<memberOf key="att.mordent.vis"/>
<memberOf key="model.ornamentLike.cmn"/>
</classes>
<content>
<empty/>
</content>
<constraintSpec ident="mordent_start-type_attributes_required" scheme="schematron">
<constraint>
<sch:rule context="mei:mordent">
<sch:assert test="@startid or @tstamp or @tstamp.ges or @tstamp.real">Must have one of the
attributes: startid, tstamp, tstamp.ges or tstamp.real.</sch:assert>
</sch:rule>
</constraint>
</constraintSpec>
<remarks xml:lang="en">
<p>The starting point of the mordent may be indicated by either a <att>startid</att>,
<att>tstamp</att>, <att>tstamp.ges</att>, or <att>tstamp.real</att> attribute. It is a
semantic error not to specify one of these attributes.</p>
</remarks></elementSpec>