This program determines the occurrence of certain religious and civil holidays and events in the Gregorian calendar year. I am by no means an authority on calendars or religious custom, and I always wondered why Easter (for example) shifted around so much. My interest was piqued when fancy calendar calculations became possible with the recent versions of Emacs, and so I followed up on the article "Calendar Calculations" by N. Dershowitz and E. M. Reingold in Software -- Practice and Experience, vol. 20, September 1990.
My selection of holidays is idiosyncratic: the Christian holidays are those recognized by my denomination (although the list is incomplete). The civil holidays are those recognized by the State of Florida and Florida State University (since those are when I have off!), and other events are just there for color and information. Jewish holidays presented are those that are listed by the authors in the above reference, and represent both major and minor holidays and feast days.
The holidays reflect current practice, not historical. That is, you will find Martin Luther King Jr's birthday listed as a holiday even if you enter the year 1843, for example. If anyone can point me to a definitive reference of historical practice, I might try to implement such a thing some day.
Careful! I am not an expert in calendar calculations, and while I have compared my results generated for several years with other references for accuracy, there may still be errors, especially with the Hebrew calendar events. If you know of other special days (other than personal holidays such as birthdays) that you would like included in this list, send me e-mail (bret at met dot fsu dot edu) with the name of the day, rules for determining the date, and the category it might fit under (e.g., miscellaneous, hebrew, christian, etc.).