The <cxxfile> element is a reference to a C++ file.
The <cxxfile> element can be used to reference a C++ file from another topic type.
<task id="connectionsxml">
<title>Connections</title>
<taskbody>
<steps>
<step><cm>Open the connection</cm>
<info>Details for the connection class are in the <cxxfile keyref="connectionfile">connection file</cxxfile>
</info>
</step>
...
</steps>
</taskbody>
</task>