Old Saradominist Calendar

The Old Saradominist Calendar uses a seven day week, whose names are as follows:

• Ivanday
• Caistleday
• Duneday
• Gullday
• Erysail
• Twiblick
• Essianday

These days first appeared in The Chosen Commander on a noticeboard in the HAM hideout.

Each day's name is taken from the name of one of the Seven Priestly Warriors. The HAM guard appears shocked when the player does not understand it, which would suggest that it is the current week used by the population of Gielinor, although it is not mentioned elsewhere and therefore unknown to players.