This seems like overkill. Sigh. We've been through this before. Existing UNIX systems do this, and as such people may expect it. Unless I see good *hard* evidence that nobody has done this and that nobody will do it, I see no reason to go through the effort of removing this capability from the code. Since the DST rules are subject to the whims of politicians and bureaucrats, any rules beyond the next year are as likely to be wrong as right. No, they're probably more likely to be right than wrong, in most cases; it *does* take a fair amount of effort, in many countries, to change those rules. I ask this because it seems to me that a file containing several years of Daylight Savings Rules can be expensive to search You don't search the file; you load the whole thing and search a table. Several techniques can be done (e.g., binary search), to make that search faster. and a program to calculate Daylight Savings time for multiple years is unnecessarily complex. No, it is *not*! The code merely searches a table; the complexity of the code is independent of the size of the table.