Adding fields for use with new abilities?

[Predictably Damaged]

I am trying to get into using the editor, and it has been, to say the least, slow going. I can't find any reference source for information about using the scripting language of the editor.

In particular, I am trying to add a racial ability which has two values that vary between races with the ability. As I understand it, those values should be set by using fields on the ability, and then having each race that has the ability set the values in those fields when it bootstraps the ability. Is this the correct approach?

If this is the right method, how do I create fields on the ability? I am getting an error that looks like this:
Thing 'raPDmgccap' - Field 'DefaultClass' referenced but not defined

Could anyone explain what is going on, and how I could implement this?