Acct-Multi-Session-Id  AVP ( 50 )

This attribute is a unique Accounting ID to make it easy to link together multiple related sessions in a log file. Each session linked together would have a unique Acct-Session-Id but the same Acct-Multi-Session-Id. It is strongly recommended that the Acct-Multi-Session-Id contain UTF-8 encoded 10646 [7] characters.

Reference: RFC 2866   View