obtain revision information

[Harry Putnam]

How can I get the current revision number of a package (module)?
And given that information, check out a version several versions
older?

Running `cvs status <ENTER>' in the checked out module gives me piles of
data on every single file in the distro.  If I run `cvs status gnus'
(This is the gnus newsreader cvs tree set up on pserver) I get a
message that cvs knows nothing about gnus.  Sort of looks like I need
to go up one level and ask, but that doesn't appear to be possible.

Is `cvs status' just the wrong command for this?

My aim here is first to determine the current version, then possibly
check out a version several versions back down the road.  Seems like I
need current info to take a guess at what revision I need or want.