I'm not sure I understand the question. Still, if you haven't used
phantom types yet, it sounds like the right thing to do:
 type 'a path = string list
 type remote_t = Remote path
 type local_t  = Local path

Now, you can write things such as

val print_local : Local path  -> unit  (*only works on local paths*)
val print_remote: Remote path -> unit  (*only works on remote paths*)
val print_any   : 'a path     -> unit  (*works with either*)

Does this help you ?

Cheers,
 David

-- 
David Teller
 Security of Distributed Systems
  http://www.univ-orleans.fr/lifo/Members/David.Teller
 Angry researcher: French Universities need reforms, but the LRU act
brings liquidations.