You need to give us a few more clues there, Andy. There can be as few or as many as you need, depending upon what you (and-or your database system) require.
For instance the GN7 document ("Guidance Note 7: Special Locations" published by the Institution of Engineering and Technology (IET)) that has been mentioned in other threads on here recently mentions only three:-1) Life support
- infusion pumps, ventilators, anaesthetic equipment and monitors etc.
- X-ray machines, CT scanners, magnetic resonance imagers, blood pressure monitors, ECG equipment etc.
- electrosurgical units, defibrillators, haemodialysis units and radiotherapy equipment etc.
On the other hand, some approaches list hundreds
of equipment types.
So, what database system are you using? What are its requirements and constraints (field lengths, and what have you)? Are you looking for generic equipment types, or manufacturer-model combinations?
How many "categories" do you have at the moment? Can you give us a few examples?
Are you thinking about a hierarchical structure, or just a simple linear approach?
Sometimes it's best to sit down with pencil and paper (plus a cup of tea, of course), and spend a bit of time planning what you want to achieve, before (and rather than simply) diving in.
In short - more information required!
This sort of thing has been discussed on here a fair amount over the years; for instance, take a look at this