We use plain English. NIMS is supposed to do away with codes for interoperability.
First response on a call of Fire = Still Alarm
Working Fire on Arrival of FD = Working Incident. We say that because it is the same terminology for any call, extrication, Hazmat, water rescue, tech rescue, etc.
Next level is a Box Alarm then 2nd, 3rd, 4th, etc.
Our area is the same as mot have stated. We use plain english. We wait for the first one on scene. It will either be nothing showing, smoke of flames showing, or whatever the percentage is involved.
Use plain english, ie. first informative when arriving (code 3)
"Coms, Pumper 343 blue, Code 3 to adam street, we have a 20m by 15m single level brick and tile house involved with fire, require 2nd station, police, ambulance and country energy also required, sitrep to follow"
We also will be updated by comms on route if it is a working fire, usually they will advise that "there have been numerous 000 calls for this incident"
We define a working fire as a fire in a structure with potential for growth. So if we are dispatched to a structure fire and it is more than a room and contents fire it is repaged as a working fire.
When we get the call, it comes in as a structure fire, our fire department got away from using the 10 code
after 9-11. Now we use plain english. It seems to work better knowing what is being said. It is also reomended by FEMA, and NIMS-ICS to use plain english at a disaster of any kind, this way when you have multiple agenies working together, they can understand one another.