Maundy Thursday April 22 inclusive, but these dates fall on different days depending on whether the Gregorian calendar or Julian calendar is used liturgically. Eastern churches generally use the Julian calendar and celebrate this feast throughout the 21st century between April 1 and May 5 in the more commonly used Gregorian calendar. The liturgy held on the evening of Maundy Thursday initiates the Easter Triduum, the period which commemorates the passion, death, and resurrection of Jesus; this period includes Good Friday and Holy Saturday, and ends on the evening of Easter. The Mass of the Lord's Supper or service of worship is
Holy Week Passion Week (the week before Holy Week) to the level of a commemoration, and in 1969 the celebration was removed from the General Roman Calendar as a duplicate of the September feast. Observance of the calendar as it stood in 1962 is still permitted as an extraordinary form of the Roman Rite, and even where the calendar as revised in 1969 is in use, some countries, such as Malta, have kept it in their national calendars. In every country, the 2002 edition of the Roman Missal provides an alternative collect for this Friday: <poem> O God, who in this season