Several people on the west coast of the US reported that their Unix systems failed to switch from daylight savings time to standard time yesterday, 26 October 1992. The reason? When they originally configured their systems, they were asked to choose one of the following time zone rules: US/Alaska US/Central US/Hawaii US/Pacific US/Aleutian US/East-Indiana US/Michigan US/Pacific-New US/Arizona US/Eastern US/Mountain US/Samoa ... Some people chose `US/Pacific-New' instead of `US/Pacific'. After all, who wants the old version when you can have the new version? Unfortunately, `US/Pacific-New' stands for ``Pacific Presidential Election Time'', which was passed by the House in April 1989 but never signed into law. In presidential election years, this rule would have delayed the PDT-to-PST switchover until after the election, to lessen the effect of broadcast news election projections on last-minute west-coast voters. Thus, US/Pacific-New and US/Pacific have always been identical -- until yesterday. This problem comes from combining Arthur David Olson's deservedly popular time zone software (which you can FTP from elsie.nci.nih.gov in pub/tz92b.tar.Z) with some overly terse vendor-supplied installation procedures. No doubt Olson did not use a more informative name like `US/Pacific-Presidential-Election' because of the 14-character file name length limit in many Unix file systems. In view of yesterday's experience, though, it seems unwise to make the hypothetical choice available under any name, since it gives free rein to Murphy's Law.