[aprssig] Spec question

J. Lance Cotton joe at lightningflash.net
Tue Jan 10 08:45:28 EST 2006

Matt Werner wrote:
> On page 23 of the APRS Protocol Reference v 1.0.1 it talks about
> latitude and longitude format.
> The examples given use capital letters for N, S, E, and W.  I do not
> see where the spec text specifically says that it needs to be capital
> letters however - the examples just USE caps.  It just says the
> "letter E" for example.
> If a packet contains a lowercase n, s, e, or w, is it considered
> correct or not?  I know some pieces of software will accept it, where
> others do not...

A while back, Bob Bruninga stated that a lowercase latitude character 
would indicate something like "An operator is present here" so that 
those who may want to send a message would know whether there is someone 
present or if it's just running without an operator at the moment.

It caused a bit of confusion because the spec didn't specify upper/lower 
case for the pre-feature situation. Some programs flagged the packet as 
a bad packet if it contained a lowercase lat/lon designator. Others 
didn't distinguish between them in any way.

I think that proposal ended up not getting anything implemented in any 
clients except that a few clients were updated to not flag the lowercase 
character as invalid.

I can't find anything about it on the "official" APRS spec 1.1 on Bob's 
website, but I distinctly remember the proposal and discussion.

Because the spec doesn't specify case, a good software developer would 
ignore case on input, but would always be consistent in packets that 
itself generates.

-Lance KJ5O

J. Lance Cotton, KJ5O
joe at lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat 
the cookies.

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