[aprssig] VARA modem replacing APRS tocall

[John Langner WB2OSZ]

I fully agree that APRS should evolve to include more functionality.
There are many examples of how this was done in the past.

The new WIDEn-N paradigm.
New extended symbols.
Extending PHG to PHGR.
NOGATE & RFONLY to prevent forwarding to APRS-IS.
IGate status reports.
APRS Voice Alert.
Reply ACK mechanism  (message id looking like {xx}xx).
Telemetry data no longer restricted to 000 to 255.
UTF-8 in comments and message text.
High precision !DAO!.
Frequency specification.
New weather fields for radiation, volts, and flooding.
Base 91 telemetry data.


Some of the new capabilities were real hacks but backward compatibility with
the existing installed base was preserved.
We should be able to find some way to add new types of properties without
violating the basic principles and breaking existing functionality.

A TNC replacing the AX.25 destination ("tocall") field would discard
valuable information and break duplicate detection.   Doing this to the
MIC-E format would be disastrous.


What is the motivation for adding the modem type to the packet?  


73,
John WB2OSZ