<grammar xmlns="http://relaxng.org/ns/structure/1.0" xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
<define name="attlist-math" ns="http://www.w3.org/1998/Math/MathML" combine="interleave">
<optional>
<ref name="dtb.smilref.attr.ns"/>
</optional>
</define>
<define name="dtb.smilref.attr.ns" combine="interleave">
<attribute name="smilref" ns="http://www.daisy.org/z3986/2005/dtbook/"/>
</define>
</grammar>