When to use _arguments -C and when to only use _arguments.

["Nikolai Weibull" <now@xxxxxxxx>]

I can't deduce from the documentation, or any of the uses, when you
would want to pass the -C option to _arguments and when you wouldn't,
assuming that you're actually going to use a state.

I mean, does it usually make sense to pass -C if you're going to use a
state, or is it the other way around?  And why?

Passing -C seems a lot more common than not, but again, I don't quite follow.

Thanks.

 nikolai