Revised text in 5.1 to eliminate an ambiguity about whether R=1 messages reset
the timer:

   MA-Hello: This message MUST be sent only in C-mode.  It contains the
   common header, with a NSLPID of zero, and a message identifier, the
   Hello-ID.  It always indicates that a node wishes to keep a messaging
   association open, and if sent with R=0 and null Hello-ID this is its
   only function.  A node MAY also invoke a diagnostic request/response
   exchange by setting R=1 and providing a non-zero Hello-ID; if this
   case, the peer MUST send another MA-Hello back along the messaging
   association echoing the same Hello-ID and with R=0.  Use of this
   diagnostic is entirely at the discretion of the initiating node.

Modified Section 1 to leave open the concept of using GIST for multicast in
certain circumstances.

Revised text:

           GIST path-coupled signalling does not directly support
   multicast flows but could be extended to do so, especially in
   environments where the multicast replication points can be made GIST-
   capable.

From Adrian Farrel:

Section 1.1 - Multicast flows 
You say: 
  Multicast:  GIST does not handle multicast flows. 
    This includes classical IP multicast and any of the 
    small group multicast schemes recently proposed. 
I think you might say that this is for future investigation 
rather than say it is not supported. You may find that GIST 
is perfectly capable of supporting multicast and is rather a 
useful tool where all replication points are GIST-capable.