Hahah I was JUST thinking about that, because I was curious about JS Burke's Proto-Central-Mountain changes (he gave me an old copy of his rules and lexicon designed for mark's SCA) and I was curious how much more concise (and fast) it would be in my format. But I realized a bunch of his rules probably require this type of treatment. I think I know how to do that.

Ok, to run it: you should be able to just navigate to the folder it's in and run it using

toolbox.bat myrules.rule

or similar. Just make sure, when you load a lexicon, the path is either absolute (starting from the drive it's on) or relatively to where you are running the toolbox from.

Square brackets aren't reserved, per se but are parsed in a special way. They are intended for use with longer variable names, like in my Kuma-Koban examples, or phonetic features which will be supported in the next version (technically they are in THIS version, but I made it so you can't load them because I want to fix some things)

And yes, you can totally do that. I should make that more explicit in the manual.