I am drawing up guidelines for 'what makes something a GIS' and I am wanting to check with the community that I have not missed anything.
I have defined a GIS by three principle points:
- Topology
- Projection
- (Spatial) Database

So it must be able to handle spatial topology, handle with projected data, e.g. UTM, or any of the ESPG codes, and thirdly store the data. I know that strictly you do not need a (spatial)database but as a guide for best practice I have included it. Are there any other aspects which are not covered by these three definitions?