seconds since the UNIX epoc (midnight, Jan 1, 1970, UTC) and is
written in base-10 notation using US-ASCII digits. The committer's
timezone is specified by `<tz>` as a positive or negative offset
-from UTC, in minutes. For example EST would be expressed in `<tz>`
+from UTC. For example EST (which is typically 5 hours behind GMT)
+would be expressed in `<tz>` by ``-0500'' while GMT is ``+0000''.