Versioning between checkout|update, commit

[Hugh Sasse Staff Elec Eng]

Still a newbie, I'd like to know how people tackle changing code
they are not ready to commit.  How does one maintain versions of
changes one has made to one's working copy of code, before one has
reached the stage of doing a commit?

It would be possible to use SCCS for this, I suppose, as I think
it's keyword tags are based on @() rather than $$, but this means
keeping two sets of commands in one's head at once, when they
perform much the same function.  I think this would be error prone.
RCS uses the same information in files as CVS and would therefor
conflict.

I've searched the faqs and the last 3 months of the list for likely
subjects, but my keyword searches were less than adequate....

        Thank you,
        Hugh