I have setup my custom field and values, and my users are updating their
documents to be assigned to the right property. But, I have come across
a problem in that some docuemnts belong to two (or more) categories. For
instance, the document 'Parental Permission Form' belongs in both the
'Elementrary Education' and 'Secondary Education' areas.

How can I assign one document to multiple values? I'm guessing the short
answer is 'you can't'! Is there some sort of workaround for this? The
only thing I can think of is to put two copies of the same document in,
and assign each one to the different properties. Not a solution I like
very much.