abbrev-mode wizardry needed

[address@hidden]

I have a huge list of unique identifiers. A person needs to enter, for
each one of those identifiers, a list of tags, and I'd like to make it
easy for them to tab-complete those tags, based on the ones they've
already entered (NOT based on an external list! They will be defining
the tags as they go.)

For example:

CAT      mammal, animal, has-whiskers, has-fur, enjoys-petting

I want to make it really easy for them to enter those properties. When
they start, no properties will have been defined yet. Each time they
enter a new one, a new property gets defined.

So, after hitting return after typing 'enjoys-petting', their cursor
will be after

DOG

I'd like them to be able to type 'm', and have some sort of way to see
the "mammal" completion on the screen somewhere, and hitting tab or
somesuch should accept the completion. If they typed 'h', they should
see both 'has-whiskers' and 'has-fur'; hitting tab should complete it
up to 'has-'; if they then type 'f', the completion list should dwindle
to 'has-fur', and ... you get the idea.

If they /delete/ a tag (so it no longer appears anywhere in the
document), it should no longer be autocompleted. (This is not a
requirement, but it would be nice.)

Can emacs/abbrev-mode do this? This is essentially equivalent to what
Excel does when you enter items in a single column, but I'd really
rather not do this in Excel for various reasons.

Thanks for any help people can provide...

Daniel Drucker