[aprssig] Auto-response position reports

[Bill Vodall]

> 3. The target station's APRS software or firmware actually implemented
> proper handling of the ?APRSP directed query.

> Andrew, KA2DDO
> author of YAAC (which does support ?APRSP)

This led to another interesting activity.   How to find, on the
APRS-IS - or better, on the air - what is the callsigns of the
stations running YAAC (or any other APRS client)?

I tried a ?APRSP to ka2ddo but no response...

>

Another interesting twist - how would a user query their local client?
  Sending a message to self?  Enter the query at the command line?
Probably varies on all the clients.

>

I found a nice list of queries at:

  http://sa7sky.net/documents/APRS-Queries.pdf

It's missing SMSGTE and WHERE but otherwise has enough to keep me busy
for a long time.

>

73
Bill, WA7NWP