From: Washington, DC
So I've been poking around with this a bit more...changing the Characteristics to 0 (or 1) does not change a unit's special abilities, nor does eliminating the attribute altogether (it auto-regenerates with a value of 1).
But when I saved the revised scenario, opened it as a game, played a turn, saved it, renamed it from a sav file to a sce file, re-opened it in the scenario editor, and exported it back to xml (whew!), it seems that some, but not all of the edited/deleted auto-regenerated to their original values. Weird...
I need to look at this further, but I'm guessing that the game (and only the game, not the editor) auto-generates these values on as as-needed basis, perhaps when a unit is within range of an enemy unit or something similar. I think that the values are based on the ability flags but something else as well, not sure what...
Will poke around for another day or two, and report my findings back here.