[boost] [variant] Why no move emulation with Boost.Move for C++03?

Hi, I am trying to figure out what the best way to enable move semantics in Boost.Optional. I tried to pick at how Boost.Variant does it. If I understand correctly, move operations are only defined if compiler supports rvalue references. I wonder why it doesn't use Boost.Move, which would enable move semantics even for compilers w/o rvalue references. Is there any reason for this (that I should also take into account for Boost.Optional)? Regards, &rzej