This may be more definitive, at least as far as the NSA's interest in the VM goes:
You are not allowed to view links.
Register or
Login to view.
The page includes the link to the above PDF as well as the link to one of the listed documents (You are not allowed to view links.
Register or
Login to view.). The other three documents aren't linked above, for whatever reason, but this group has found copies of them elsewhere.