[aprssig] Message reject behavior

[scott at opentrac.org]

What's the expected behavior, if any, when a station receiving a message
responds with a :rej rejection?  The spec just says a reject should be
returned to indicate the message was not accepted.  I'd expect the sending
station to stop trying, but Xastir and my D7 at least don't - they keep
resending.  I was hoping to use the :rej response to indicate authentication
failure when sending commands, but it doesn't look like a viable option.

And if :rej doesn't work, that leaves :ack, and I need some way to indicate
that the command was refused.  I'd prefer to do the message-ack thing rather
than have to send two packets, but I've heard the Kenwoods don't support it.
Are there any other clients out there that don't support combined ACKs?

Scott
N1VG