Last month we posted a story about the changes to Daylight Saving Time coming up in the US. A few customers have asked HP to make changes in the TZTAB.LIB.SYS file in MPE/iX, because DST will  start and end on different weekends in 2007 than it has up to now. TZTAB carries the keys to the HP 3000's time zone information. The HP-UX environment already has its zone patches.

But our advice which told users they'd need a C compiler to make these changes themselves was off base, according to one customer. A well-informed customer at that. Walter Murray used to work in HP's languages lab on the 3000 and other servers, including expertise on HP's COBOL II. Murray cleared up the confusion for us.

In the article “OpenMPE thinks far ahead of time changes” (August, 2006), you imply that a customer would need a C compiler to make the necessary changes to the file TZTAB.LIB.SYS to accommodate the change in Daylight Saving Time rules.

Not so! TZTAB is an ordinary ASCII file. You can update it with the editor of your choice.

Another important point is that it’s not just C programs that are likely to rely on the TZTAB file. For example, COBOL programs that use the CURRENT-DATE function will also want the TZTAB file to be correct.

Thanks to Walter for making this issue clear. HP still has a little while to apply such a patch to MPE/iX TZTAB —  a change that ought to take place for all supported MPE versions, 6.5, 7.0 and 7.5.

But it's good to know that the capability to do the work yourself lies in the hands of many users who don't have C compilers on hand.