There was a time where I was comparing what Xastir does to the 1.0.1
APRS spec and was confused because we aren't displaying the objects
with the sizes that 1.0.1 spec says. That's because the 1.0.1 spec is
outdated and was overridden by a "1.1 addendum", which Xastir follows
just fine.
When I wrote this article I was still confused and peppered it with
comments about how we're not spec compliant. However, when I got
straightened out about that, I didn't correct all of those comments.
I'm correcting them now.
We are not, however, spec compliant on the *placement* of area
objects, which we draw up and to the left of the point specified,
where the spec specifies other orientations (down and to the right for
rectangles and the bounding boxes of circles). We don't draw circles
according to spec either (we put the circle around the point
transmitted, where the spec says the point transmitted should be the
upper left corner of the bounding box), and neither do we get
triangles right, either.
The APRS spec document "APRS101.PDF" is obsolete and contains
incorrect information. One of those bits of incorrect information
happens to be related to area objects, exactly the issue I griped
about yesterday in the Area-Objects page.
Turns out Xastir *IS* spec-compliant, but to the "1.1 addendum" of the
spec. The "1.1 addendum" is just a web page of rambling text
documents from Bob Bruninga's old web site. You have to read that
stuff, not just rely on the PDF spec.
Yeesh.
Fortunately, John Langner has a repo where he is working on collecting
all of those addenda into an updated spec document.
Link there.
