[aprssig] New n-N Digipeater Overlays

[Robert Bruninga]

Thanks to feedback from Dick, we slightly revised the New n-N 
overlays to clarify a few things to cover all combinations of n-N
and resolve how to handle UIDIGI and DIGI_NED:

http://cadigweb.ew.usna.edu/~bruninga/aprs/n-n-overlays.txt 

Here is the new version:

DIGIPEATER OVERLAY CHARACTERS for the new N-N PARADIGM     12 Dec 2004
----------------------------------------------------------------------

Revised 4 Jan 2004 to clarify the U and D overlays...

To keep users informed of the changes by this new n-N paradigm, we 
should label our new digis in a consistent manner for the benefit of 
the users.  If the digi retains WIDEn-N and has neither a State SSn or
Link LNKn, then leave it as an "N".  Otherwise, if you drop WIDEn-N
then these characters might be best:

N overlay for WIDEn-N's     "R,W,Wn" in LText (if neither SS or LNK)
S overlay for Wn-N & SSn-N  "R,W,Wn,SSn" in LText for W and 1 state
K overlay for Wn-N & LNKn-N "R,W,Wn,##Kn" in LText for interstate ##
D overlay for dual SSn-N's  "R,W,SSn,SSn" in LText for two states
X overlay for dual LNKn-N's "R,W,##Kn,##Kn" for two Interstates
L overlay for LAN/LINKn-N's "R,W,##Kn,SSn" for Interstate and State

I expect most if not all such digis will actually be just the "L"
variety except for the crossing interstate "X" or the dual-state
"S" digis.  But where WIDEn-N can still be supported, then use the
S and K to show shared use with WIDE.

Of course we keep some of the existing overlays:

R  for RELAY only digis
W  for WIDE or RELAY,WIDE only digis
T  for PacComm TRACE digis with callsign substitution 
N  overlay for WIDEn-N's,  "R,W,Wn" in BText
U* for UIdigi       *Should use the New n-N overlays
D* for DIGI_NED     *Should use the New n-N overlays.

We do not need to distinguish UIDIGI and DIGI_NED anymore, since
they also can do the New N-N paradigm and we can tell their software
type in the UNPROTO TOCALL which should be APNU.. or APND..

de WB4APR, Bob