Re: Calendar hack: Displaying ISO weeks, update for emacs 22, the real update

[Richard Stallman]

    How do you know that the holidays are correct when the calendar has more 
than
    3 months?  Do you have a way to check, say, the dates of lunar phases, 
Easter,
    Chinese New Year, Yom Kippur, Islamic New Year, solstices/equinoxes?  You 
will
    see SOME holidays (or diary entries) but not all that apply to the months
    displayed.

One easy way to check is to run the standard calendar code (without
this customization) and see if it indicates the same holidays.