CVS: Get the state of some branch in some date

I have a big project with branches. All development is concentrated in the branch. I want to get the state of this branch at some time ago, but can't

 cvs up -r branch_name -D 2010-05-01

gives me (in cvs status Makefile) the sticky tag, but the newest version of file, not at 2010-05-01

 cvs up -D 2010-05-01 -r branch_name

ignores a tag and updated to that Date of the HEAD

 cvs up -r branch_name:2010-05-0开发者_开发百科1

doesn't work too, it ignores date and updates to current state of branch.

cvs update -PdC -r BRANCH-NAME-HERE -D "Saturday, May 1, 2010 0:00:00 AM UTC"

If you know the time, add that...

This should do the trick:

cvs up -r branch_name:2010-05-01

The colon syntax is only documented for the -j option but probably works for -r, too.