full userdata guaranteed to not move?

[Josh Haberman <jhaberman@...>]

I asked a question a while back about Lua strings and whether the API
guarantees that their address will remain fixed.

http://lua-users.org/lists/lua-l/2011-06/msg00383.html

The consensus was that the API only guarantees that strings stay put
while they're on the stack; at any other time a moving GC is allowed
to relocate them (even though no implementation does this currently).

Now I'm wondering the same thing about full userdata. Unlike
lua_tolstring(), lua_touserdata() contains no warning about pointers
becoming invalid when the userdata is removed from the stack.

Does this mean that userdata are not allowed to be moved, even by a
theoretical future moving GC?

Thanks,
Josh