non-gregorian calendars [was: ical schema...]

On Fri, 2002-12-20 at 23:28, Charles McCathieNevile wrote:
[...]

> Planning according to menstrual cycle. This is something that real people do.
> Often these will follow a lunar calendar, in which case an islamic calendar
> works, or they will be regulated on a strict cycle of 28 days.

A 28 day month sure makes a lot more sense; the story
I heard was that pope gregory thought 13 months
in the year was too pagan or something so he had
to deploy something different. And the rest, as
they say, is history.

By the way... speaking of calendar arcana, I happened
accross this FAQ one day...

Frequently Asked Questions about Calendars 
Version 2.4
Claus Tøndering
28 October 2001
http://www.tondering.dk/claus/cal/calendar24.html

and it was so fascinating that it was several hours
later before I realized the time had gone by.

Perhaps something to link from the calendaring
workspace... bonus points if you beat me to it.

> Finding Easter. For non-orthodox churches (which is my own use case, and
> therefore the one I am most familiar with) I believe this can be readily
> determined with only a lunar calendar, a solar calendar, and a jewish
> calendar (I need to know the first full moon after the equinox, and then
> whether or not pasoch falls on that date).

A practical implementation strategy for this sort of thing...

I gather these things often actually depend on astronomical observation,
in which case there's no hope of computing them locally without
doing some I/O. And if you're going to do I/O, you might as well
do an HTTP GET to some trusted source that maps "the next easter"
to a gregorian YYYY-MM-DD. This is the same approach
I use to map city names and airport codes to lat/long;
e.g.
  http://www.w3.org/2000/04/mem-news/teamToGlobe


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Saturday, 21 December 2002 13:36:59 UTC