The easiest way to create instrument definitions for typical brass-body/molded-head whistles like Generations, etc., is to start with the definition in the file FeadogMk1.xml in the instrument samples that come with WIDesigner, in WIDesigner-2.5\WhistleStudy\instruments\FeadogMk1.xml. Modify this definition with measurements from your chosen whistle, and save it with a new file name. Wooden and synthetic whistles will require more substantial changes, but you can still start from the same place.
I took a shot at explaining the terms in the
Glossary. I agree that a diagram would be very helpful, but my drafting skills aren't up to creating that drawing without some painstaking work. Regarding the tube diameter, the I.D. appears as the "bore diameter" in the list of bore points. The O.D. does not appear explicitly except as the "termination flange diameter". However, the height measurements for the holes will be half the difference between the O.D. and the I.D. If the I.D. is 12.0 mm, and the O.D. is 12.7 mm, the hole height will be 0.35 mm, the thickness of the brass tube.
The sample tunings, in WIDesigner-2.5\WhistleStudy\tunings, include files for high D (D5) and mezzo A (A4) in Just Intonation and Equal Temperament, and low D (D4) and mezzo Bb (Bb4) in J.I. For just about any high D whistle, D5-Equal.xml is a good place to start.