I think it's simply reserved, like a few other words, for future implementation. This should prevent us from accidentally using it ourselves, then having our code break if/when it would get implemented.

It might also be a matter of a Java syntax highlighting file being used with some edits and some leftover bits, I've seen a few of those as well.

...or both might be the case :-), at any rate; I don't think there is a "case" structure for us to use right now.

Yours,

Kas.