I have XML with a bunch of different processing instructions in them; here
is a sample:

<?xml version="1.0" encoding="UTF-8"?>
<info>
    <?Fm Condstart VbV-VCO?>
    <p>For this, use <b>that </b>to do that.</p>
    <?Fm Condend VbV-VCO?>
    <p><?Fm Condstart USB?>If you need this, do that.<?Fm Condend USB?></p>
</info>

For each "pair" of processing instructions (Condstart and Condend with the
same string), I want to find all of the nodes between them.