[aprssig] Universal APRS messaging

[Robert Bruninga]

I am excited about all of these methods for sending APRS
messages, but I think that browser based systems need an
authentification system.  Users should have to set up an
"account" so that they can establish a PIN number or something
to authenticate.

Another thing we can do is have any such message generated by a
non-RF device insert its own identificaiton in the message.  My
thoughts are in the LINE number field.  There we can use the
last two bytes as an identifier, insert {xxxFU for Findu, or
{xxxFI for Finland or whatever.  This is because the radios
display at least the last two bytes of the line number.

Bob, WB4APR