As I am literally old school, I also do everything thru text files and follow the semantic model in this. To ease things a bit I start all location groups with lg, equipment groups with eg and all groups outside the model with just a g
lgGroundfloor, lgLivingroom
egBathroomlights, egFloorheating etc.
I also keep them in separate files :
groupslocation.items
groupsequipment.items
groups.items
This helps me a lot with finding the correct group