Editing OpenMath (section)

== Example ==

The well-known [[quadratic formula]]:
:<math>x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}</math>

would be marked up like this in OpenMath (the representation is an expression tree made up from functional elements like {{mono|OMA}} for function application or {{mono|OMV}} for variables):

<syntaxhighlight lang="xml">
<OMOBJ xmlns="http://www.openmath.org/OpenMath">
  <OMA cdbase="http://www.openmath.org/cd">
    <OMS cd="relation1" name="eq"/>
    <OMV name="x"/>
    <OMA>
      <OMS cd="arith1" name="divide"/>
      <OMA>
        <OMS cdbase="http://www.example.com/mathops" cd="multiops" name="plusminus"/>
        <OMA>
          <OMS cd="arith1" name="unary_minus"/>
          <OMV name="b"/>
        </OMA>
        <OMA>
          <OMS cd="arith1" name="root"/>
          <OMA>
            <OMS cd="arith1" name="minus"/>
            <OMA>
              <OMS cd="arith1" name="power"/>
              <OMV name="b"/>
              <OMI>2</OMI>
            </OMA>
            <OMA>
              <OMS cd="arith1" name="times"/>
              <OMI>4</OMI>
              <OMV name="a"/>
              <OMV name="c"/>
            </OMA>
          </OMA>
        </OMA>
      </OMA>
      <OMA>
        <OMS cd="arith1" name="times"/>
        <OMI>2</OMI>
        <OMV name="a"/>
      </OMA>
    </OMA>
  </OMA>
</OMOBJ>
</syntaxhighlight>

In the expression tree above symbols—i.e. elements like {{mono|<nowiki><OMS cd="arith1" name="times"/></nowiki>}}—stand for mathematical functions that are applied to sibling expressions in an {{mono|OMA}} which are interpreted as arguments. The {{mono|OMS}} element is a generic extension element that means whatever is specified in the content dictionary referred to in the {{mono|cd}} attribute (this document can be found at the URI specified in the innermost {{mono|cdbase}} attribute dominating the respective {{mono|OMS}} element. In the example above, all symbols come from the content dictionary for arithmetics ({{mono|arith1}}, see below), except for the {{mono|plusminus}}, which comes from a non-standard place, hence the {{mono|cdbase}} attribute here.