question on size of reservation id

do we really need 32 bits of reservation id?
would 16 bits suffice?  since reservation ids
are a global resource as opposed to a port
resource, i am concerned that it might be too
small a value.  but the concern for  parsimony
dictate that i should at least ask.

the questions comes in the context adding
a (result,code) byte to every transaction
in a bulk msg.

assuming that bulk msgs would only
be supported when there was a prexisitng
complete reservation, that would give a
trigger msd of

[header] x 3
[port session id]
[reservation id, result, code]

and a bulk msg

[header] x 3
[port session id]
[reservation id, result, code]
.
.
.
[port session id]
[reservation id, result, code]

that is, of course assuming that a bulk msg
can  support transactions on multiple ports.
we could also define it to support msgs on
on single port per bulk message.

would anyone who has implemented already
object to such a change?

a.