AREA OBJECT NOTES (APRS 1.0)                                     Dec 1999
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                                                                   WB4APR

Here are some notes about area objects as written in the spec.  These 
notes were derived from comments by Curt Mills while attempting to follow
the spec:

* Ellipses haven't been implemented in any software yet...

* Triangles are always isosceles triangles, oriented vertically...
  and the points of reference are the top APEX and the lower right corner.

* Circles are defined by a square box referenced by the upper left corner
  and the center.

* Lines are referenced to the upper end.

The Spec is WRONG about how the LAT/LONG of the object is derived.
The last paragraph on the bottom of page 60 SHOULD SAY:

"The 'offset reference' position of the object is the upper left corner
of the object and the offsets are the distance from the lower right
corner (or center of a circle) back to this "offset reference" position.
(An exception is the special case of a type-6 line which is drawn down
and to the left)."

As written, the spec implies that the LAT/LONG of the offset reference
position is actually what goes in the packet, but in fact, it is the
lower reference point that is the actual transmitted lat/long of the
object.

* The Formula for sizing is wrong in spec.  Should be: 
offset_in_degrees = (offset_in_packet^2) / 1500 

de WB4APR, Bob