[Dstar] Another question on multiple radios

[Michael Carey]

Hi Everybody,
I'm still reading through the various forums (Icom D-Star and K5TIT 
forums) and have gained heaps of useful info on D-Star.
I can understand how users need to be entered into the "system" to be 
able to talk to users on other D-Star repeaters, but what is the 
situation when an amateur has multiple D-Star radios? I would like to 
have an IC_2820H in my Hilux, a IC-91AD for when I'm feeling energetic 
and want to walk around, and then possibly something at home and maybe 
at work as well.  Is there something similar to a SSID used in packet 
radio that can be appended to the callsign programmed into the radio? If 
this is the case, does each callsign need to be entered into the "system"?
I hope this isn't a dumb question...
Michael.
VK5ZEA