[aprssig] Roundthe-world approaching Cancouver Island now!

[John Langner WB2OSZ]

The telemetry format is a little perplexing.

After discovering http://he.fi/doc/aprs-base91-comment-telemetry.txt, we can
understand this:

M0XER-3>APRS63,WIDE2*,qAR,VE7VMH:!//xOy0<xtO JioE/A=041397|y6OV&s<W!,|

The part between the | characters, in the comment field, is the base 91
representation of the telemetry values.

The protocol spec indicates that we still need the original special
"message" packets for the metadata such as field names, scaling
coefficients, and units.  I don't see them anywhere.

However we do see less frequent longer packets like this:

M0XER-3>APRS63,WIDE2*,qAR,VE7VMH:!//w{W0=T:O
Jiq1.tJ57Q+UnByC(\Gb:$Yw>z/A=041420|y9OR&\<[!)|

What does ".tJ57Q+UnByC(\Gb:$Yw>z" represent?   Is this the metadata in some
new compressed format?  Where is it documented?