24:00 versus 23:59:59--another possibility

[Olson, Arthur David (NIH/NCI) [E]]

Yet another possibility is to add a special case to zic to treat instances of 23:59:59 as if they were 24:00; this lets us use 23:59:59 in input files to make pre-1998 versions of zic happy and to get correct-to-the-second results out of post-2009 versions of zic.

        --ado