<?xml version='1.0'?>

<example>
    <OMOBJ xmlns="http://www.openmath.org/OpenMath" version="2.0">
       <OMA>
          <OMS cd="math4all" name="difference" cdbase="math4all"/>
          <OMA cdbase="http://www.openmath.org/cd">
             <OMS cd="relation1" name="eq"/>
             <OMV name="y"/>
             <OMA>
                <OMS cd="arith1" name="minus"/>
                <OMA>
                   <OMV name="f"/>
                   <OMV name="x"/>
                </OMA>
                <OMA>
                   <OMV name="f"/>
                   <OMA>
                      <OMS cd="arith1" name="minus"/>
                      <OMV name="x"/>
                      <OMI>1</OMI>
                   </OMA>
                </OMA>
             </OMA>
          </OMA>
       </OMA>
    </OMOBJ>
</example>
