There's nothing wrong with classifying and categorizing the kit, John ... and I say that having spent many hours (hundreds, thousands?) over the years doing just that ... just as long as the folk doing the classifying make a good job of it.
And I write as one who has suffered the consequences (usually in the form of extra - unnecessary - work) of it being done badly as well. Back in the army, for example (they were forever plonking lab kit under "general medical" ... and once the numbers had been assigned it was nigh-on impossible to get them corrected). And also on various overseas projects (they almost always got it wrong ... and we were forever having to "cross refer" to more sensible lists).
For those who have never tried it, I would advise that (just like writing specs) it's not as easy as it may first appear.
Don't forget that others have had a fair crack at it over the years. ECRI for example.
So, questions that come to mind are:-
1) Why not use the ECRI codes (they are in use worldwide)?
2) Who are these GMDN people anyway?
3) Are they a government agency (or a money spinning company)?
4) Do you want to rely on them (to be beholden to them)?
5) Can we be sure that they'll always be around?
6) How much does it all cost?
7) Why can't the National Health Service do this sort of thing for themselves (and have their own codes)?
Others tuning in may also be wondering:-
1) What are these guys talking about?
2) Why does the kit need to have codified anyway?
3) What purpose does it serve?
4) Does it relate to tech support and maintenance (or just "property control")?
5) Is it that important that (lots of) time needs to be found to carry it through?
... and stuff like that!
Lastly (and it sounds like you have already done this, John) I would suggest that folk always retain a mechanism to be able to assign their own
codes in cases where the "official" ones don't really fit ... or are just plain wrong!