When to use DST rules

[seismo!nbires!vianet!devine]

dreamit!jjw suggests:

1. [more than a year or two of DST rules is overkill]
2. "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."
3. "a file containing several years of DST Rules can be expensive to search
  and a program to calculate DST for multiple years is unnecessarily complex."


  I agree that providing all rules of all years is overkill for most users.
But who can say beforehand which rules are needed by a particular site.
Consider how termcap/terminfo entries are provided: All possible terminal
descriptions are distributed but a user can remove any unneeded descriptions.

  It is not correct that DST rules are completely unfathonable.  Yes, they
do change and one can only guess what the DST rules will be in far distant
years.  This only means that changing the DST database should be quicker and
easier to do than for the "politicians and bureaucrats" to pass laws.

  So, the rule should be to provide an implementation with sufficient
flexibility so that a user can use it with all rules or just those
that are wanted.  Don't decide for someone.

Bob Devine