[aprssig] APRS spec location and version (was: Re: are new symbols intended to be supported yet?)

Pete Loveall AE5PL Lists hamlists at ametx.com
Wed Dec 4 10:35:34 CST 2013

The only true "spec" is 1.0.1 from the TAPR web site.  All others are additions/clarifications made by Bob and others.  In fact, the 1.0.1 spec is not "buggy" but did need some clarifications (and yes, there are some "grey" areas which have also been clarified, primarily on Bob's web site).  As I said, Bob's web site does have some good clarifications and additions; it just isn't the spec.

I agree that Bob's unilateral statements of "this is the spec" on his web site can be very confusing to the people writing APRS software (and to users).  But I go back to my prior statement:

My recommendation: write to the spec, not Bob's web site and then add features from Bob's web site as you see fit.  Bob's web site does have some good clarifications of the spec and additions but they are not "the spec".  Also understand that there are and will be many clients that will not implement many of those "new features".

As to "Where is that difference between D-PRS I-gate symbol and D-star repeater symbol documented?", the more proper question is "What is the difference between a D-PRS IGate and a D-STAR repeater?" and that is documented many places.  APRS symbols (and AX.25 SSIDs, for that matter since it always comes up in these discussions) are a baseline (gate symbol, red diamond symbol, etc.).  How someone uses them is up to them.  The overlaid symbols like the gate symbol and red diamond symbol have different meanings to different people depending on the overlay.  For instance, the gate symbol is used by IRLP to indicate status by changing the overlay!  And there are IGates still using the TCP symbol.

While it would be nice to say "This is an absolute", many things in APRS are not absolute and that actually makes it more flexible than a protocol that requires a committee changing the specification every time someone wants to use a symbol differently, for instance.  The specification gives the baseline that all can write to and ensure some level of compatibility between clients.  The "addendums" produced by any single person need to be understood to be just that and software authors need to keep that in mind as they look at implementing any of those features.  Some clients will implement the new, some won't, and some can't.


Pete Loveall AE5PL
pete at ae5pl dot net

> -----Original Message-----
> From: Andrew P.
> Sent: Wednesday, December 04, 2013 10:12 AM
> OK. So the next question is: where is the spec, and what version are we at?
> Obviously, we're beyond APRS 1.0.1, but are we at 1.1 or 1.2 (or later)?
> All the websites referring to the spec either have a copy of the buggy original
> 1.0.1 spec, or a link to an appropriate page on Bob's website.
> It's exceptionally confusing in that Bob has started a 1.3 proposals page
> (completely blank as of now), which would seem to imply that 1.2 is finalized.
> Anyone got an idea what the official spec is and where?
> P.S. Where is that difference between D-PRS I-gate symbol and D-star
> repeater symbol documented?

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