Some colleagues and I would like to put together a grammar compendium to teach English grammar and would like to record the rules and examples in XML so as to increase the kinds of ways it can be utilized.
As with any XML, much of the work is defining the schema, what to leave out and what to leave in. Here is an example of the kind of XML we are looking to create:
<grammarUnit>
<title>Present Perfect</title>
<rules>
<rule title="Past actions with results/consequences in the present">
<examples>
<example answer="has eaten">Paul _____ all the cookies.</example>
<example answer="has gone">Paul _____ to the basketball game.</example>
</examples>
</rule>
</rules>
</grammarUnit>
Does anyone know of an XML like this that represents grammar rules? (It's hard to search Google for this since XML is itself a kind of grammar which brings up many unwanted hits.)

____as the placeholder, use an XLM element instead (which could hold the answer itself). – Joachim Sauer Mar 2 '12 at 6:53