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Traditionalist Catholic religious communities still use this calendar to a certain extent.

At the beginning of dinner, the seminarians will assemble in the refectory and listen to the daily reading of the Roman Martyrology. It begins, for example, with "A reading from the Roman Martyrology for the fifth day before the Kalends of February, the thirteenth moon." Thereupon, we would hear about the saints whose feast days were established for the following day. The reading would end with the words "and elsewhere, many other holy martyrs, saints, and holy virgins."

The oddest day in the calendar was the dies bisextus, which gets inserted somewhere after the Nones of February in leap years. On that day, the reading is simply "Many holy martyrs, saints, and holy virgins."

To this day, indult parishes that celebrate the 1962 Roman liturgy have saints days that get moved apparently arbitrarily in late February on leap years. If you understand the old Roman calendar, it makes sense.