My paper on free choice and imperatives is coming out in L&P and is up on the website now. Here's a link to the archived version: philpapers.org/rec/CARFAC-9.
tl;dr: you can learn a lot about the difference between ordering and permitting by thinking about literally `anything'.
Minds & Machines = Birth of Cool
Models & Reality = Milestones
The Meaning of `Meaning' = Kind of Blue
Reason, Truth & History = Bitches Brew
Representation & Reality = Everythings Beautiful
A contrast that @_sjbc and I considered:
a. When Al was last in CA, he went to the beach.
b. *Now that Al was last in CA, he went to the beach.
c. When Al was in CA in 97, he went to the beach.
d. *Now that Al was in CA in 97, he went to the beach.
What's up? Syntax, semantics?