The <apioperation> element is a reference to an operation.
This element can be used to reference an operation from another DITA topic type.
<task id="httpxml">
<title>Getting an XML file through an HTTP connection</title>
<taskbody>
<steps>
<step><cm>Open the connection</cm>
<info>You use <apioperation keyref="com.ibm.xtools.patterns.framework.uml2.PlugletException.notify">Notify method</apioperation>
in a VB6 application.</info>
</step>
...
</steps>
</taskbody>
</task>