As one who doesn't use zic, my preference is to do it "properly" with 24:00 - but other non-zic based users may have problems with this. Perhaps the best thing is to use 24:00 but to comment it forusers of old zic releases or other users for whom this causes a problem? Tim Smartcom Software Ltd Portsmouth Technopole Kingston Crescent Portsmouth PO2 8FA United Kingdom www.smartcomsoftware.com Smartcom Software is a limited company registered in England and Wales, registered number 05641521. -----Original Message----- From: Olson, Arthur David (NIH/NCI) [E] [mailto:olsona@dc37a.nci.nih.gov] Sent: 28 April 2009 12:54 To: tz@lecserver.nci.nih.gov Subject: 24:00 versus 23:59:59--another possibility 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