I can offer no help on your questions above, but it may help to
examine the output of AIRSPACE.EXE. Of course that program no longer
works with unmodified Edition 9 USFIF files, but I have had success
running AIRSPACE.EXE by making a simple substitution on the values on
in the Shap column in BNDRY.TXT. I used a text editor to change
TABBTAB to TABHTAB in that file, and now AIRSPACE seems to
work OK. Evidently "B" is a new value that appears in the newer
editions that is not supported by AIRSPACE.EXE.

2KA