NUMBER RANGES

a unique reqt is ahead please help me in this

we have a reqt that to maitnain number ranges specific to orgnizations.

ex we have a slaes org in delhi and chennai

now our client want the orders to be genrated at delhi to be tagged as DL001

and at chennai as CH001,CH002,CH003 how to do this it shdnt b external number range

it should be internal as a character in it and org specific please help me in this

REWARDS DEFII..

thanks .