Cisco and RADIUS

Hello all I am new to RADIUS. I am using Cisco IP IP gw as NAS and RADIUS. I have few doubts regarding the interaction between CISCO and RADIUS Whenever the request for authentication comes, for all authenticated users I wish to send some extra details like Billing model, credit time etc. If I make changes in the authentication query to return these values, how will the nas understand that which one is billing model or which one is credit time. Do I have to make any changes in the Dictionary or RADIUS. I tried to search for the same in CISCO site but hard luck couldn't find it. Please guys help me out Thanks in advance Vignesh