Copyright © 2022 Denis A. Elliott
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InterCal is a date conversion program and perpetual calendar. It is not a personal appointment calendar.

The program displays calendars, one month at a time, for any month of any year in any of nine implemented calendar systems. For each day, the corresponding date in any other system can be shown—thus an entire month is converted at once.

Any single day can be selected and its equivalent listed in all systems.

Certain Christian, Jewish, and Islamic holydays can be highlighted if the user wishes.

Starting with version 2.1—the user can define his/her own days to be highlighted.

Implemented systems are:

• Gregorian
• Julian
• Western Historical (a hybrid of Gregorian and Julian)
• Jewish
• Islamic
• French Revolutionary
• Chinese
• Mayan
• Persian
• Afghan
• Elliott Super

InterCal is localized for English and Dutch. Thanks to Frans van Bodegom for the Dutch.