[aprssig] alt input digipeater

[Robert Bruninga]

>I was trying to think of a way to indicate... that alt input is
>available on 144.99....what if we agreed on a specific 
>PL tone... You could LISTEN on 144.39 for a  pl tone, 
>and know that you are in an area that has 144.99 alt input.

This is already covered in the plan.  All 144.99 input digis
are supposed to use a tactical callsign of 99XXXX.  For
example, in Annapolis, it is 99ANAP and shows up right
on the front panel of the mobile users radio... Easy. Done

See the plan for Alt-Input Digis:
http://www.ew.usna.edu/~bruninga/aprs/altchannel.txt

de Wb4APR, Bob