Please note that using a a parser like Xerces is not acceptable. You can either describe the algorithm, write pseudo code or optionally implement the solution.
Describe how to implement a simple parser that does well-formedness checking on XML, such as the following:
<BackgroundCheck>
<CriminalHistory>
<HistoryCode>x</HistoryCode>
<HistoryCode>y</HistoryCode>
<HistoryCode>z</HistoryCode>
</CriminalHistory>
</BackgroundCheck>
