I think I did not expess myself too well.
I am trying to search the GMDN list for equipment and cannot find certain simple things such as air mattresses - it does have have overlays. (I have paid for access to the official site)
I was wondering if anyone had a simple way of working out what heading things come under. If you start at the top and work down the tree (albeit an up side down one) I end up with not the item I wanted. there seems to be no logic at all in the groupings of equipment and there seems to be multiple paths to the same item. As you can tell I am new to this system and am struggling to understand it.
Any experienced people out there or is it really a mess as I am beginning to suspect?
I thought the collective terms were hierachical but it seems they are not. Am I right?

My spelling is not bad. I am typing this on a Medigenic keyboard and I blame that for all my typos.