Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0
RCS's internal timestamps are always UTC, so that people in different timezones
can collaborate. I assume by "date stamp" you mean "$Id$" and the like? They're
UTC too, I think. I suppose RCS could add an option to change this, but the
default should remain UTC.