<sch:report test="@from and @target">Only one of the attributes @target and @from may be supplied on <sch:name/> </sch:report>
Schematron
<sch:report test="@to and @target">Only one of the attributes @target and @to may be supplied on <sch:name/> </sch:report>
Schematron
<sch:report test="@to and not(@from)">If @to is supplied on <sch:name/>, @from must be supplied as well</sch:report>
Schematron
<sch:report test="contains(normalize-space(@to),' ') or contains(normalize-space(@from),'
')">The attributes @to and @from on <sch:name/> may each contain only a single value</sch:report>