Content-calculus.class

<xs:group name="Content-calculus.class">
  <xs:choice>
    <xs:element ref="int"/>
    <xs:element ref="diff"/>
    <xs:element ref="partialdiff"/>
    <xs:element ref="limit"/>
    <xs:element ref="lowlimit"/>
    <xs:element ref="uplimit"/>
    <xs:element ref="tendsto"/>
  </xs:choice>
</xs:group>