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[aprssig] aprssig Digest, Vol 89, Issue 5

Brent Hildebrand brent.hildebrand at gmail.com
Sat Nov 5 13:49:02 UTC 2011

Line numbers are of the form {xx.  Reply/Acks }yy.  A Reply/Ack is not a
linenumber and should not be interpreted as such.  Thus, an exchange with
one user having AA turned on might look like this:

WB1XYZ>APRS::KK2ABC   :Hello there! {06
KK2ABC>APRS::WB1XYZ   :ack06
KK2ABC>APRS::WB1XYZ   :AA:I'm not here }06

There is no line number in the AA message, only a Reply/Ack. If KK2ABC
returns to their keyboard and send a reply, the exchange might like like

KK2ABC>APRS::WB1XYZ   :I'm back! {02}06
WB1XYZ>APRS::KK2ABC   :ack02}06
WB1XYZ>APRS::KK2ABC   :Good to hear from you {07}02
KK2ABC>APRS::WB1XYZ   :ack07}02
WB1XYZ>APRS::KK2ABC   :Where have you been? {08}02
//  KK2ABC leaves again and turns on the AA message...
KK2ABC>APRS::WB1XYZ   :AA:I'm not here }08

The point is, that a reply/ack can be added to a AA message and it should
not be interpreted as a message number because it is not of the form of a
message number.

Old client programs, the message number was of the form {xxxxx.  When
reply/acks were added to newer programs, they did not break anything.
Generating the real "ack" as :ack02}06 is only ack'ing message number 2.
On programs that understand reply/acks, ;ack02 would have been sufficient.
For backward compatibility, the ack included the reply/ack. Putting the
reply/ack in the AA does not cause backward compatibility issues because
the reply/ack is not in message number format and should not generate a
return ack.

OK - I'll disappear again.  This is probably not that important.  BH KH2Z

On Sat, Nov 5, 2011 at 5:00 AM, <aprssig-request at tapr.org> wrote:

> Bob's 2) precludes that.  The "ack" request }nn is the same thing as a
> "Line number" which Bob says that AA's should NOT have.
> Unless you're referring to an APRS client implementation that actually
> issues such ack requests on it's AA (without the colon) packets?  You
> didn't give us much context here.
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