(2017-05-10)
Problem
How to retrieve an old version of the config file?
Solution
Don't do this in your current tree, create a new one:
$ mkdir ~/tmp/xx
$ cd ~/tmp/xx
$ cvs -d ~/var/CVS co -r 1.2 company/configs/router
That should check out revision 1.2 of router into ~/tmp/xx/company/configs.