resettodr(9) on FreeBSD
The text 3b6981bbb4f7, as FreeBSD 3.5.1-RELEASE, FreeBSD 3.5-RELEASE, FreeBSD 3.4-RELEASE, FreeBSD 3.3-RELEASE, FreeBSD 3.2-RELEASE, FreeBSD 3.1-RELEASE, FreeBSD 3.0-RELEASE shipped it.
set battery-backed clock from system time