how to return attribute with more than one value in an access-accept packet?

Hello, all! Now I use fr 2.19 for our WiMAX network. It works well now! Thanks for all who have helped us on this maillist. however, I still have an important question. Our vendor asked us to return some attributes which are listed in WiMAX Forum Standard as return 0-n or 1-n. That is, in a single access-accept packet, there may 2 or 3 value for attribute like "Packet-Flow-Descriptor", "Time-Of-Day-Time". I don't know how to achieve this? Thanks in advance for your kindly help!