instruments.xml

Should tags be case sensitive
ChurchOrganist's (current) sample file already fails on two points, no "museScore" tag, only "musescore" and one (so far) musicXMLId instead of MusicXMLid.
Overly sensitive checking? I'd say so. What do you think
And then, what should happen when an unknown tag is found. Currently it aborts.

This is basically the open/closed situation. If control data is only supplied, not editable, then strict checking like this is fine because the user can't make a mistake. It's arguable that the tags shouldn't be user editable, in which case strict checking like this is also valid.
Personally I don' think it's a good idea, but I thought I'd ask the question.