This is a solar calendar, which dates from a time in ancient mythology when "the first God-Men stepped onto the earth", tens of millennia ago.

It is virtually unknown outside the archives of the Rasian Academy, but many of the most ancient documents use this scale, including the records of Rasian Masters.

Although it is largely obsolete it has some practical applications today. Since years in HM are numbered in cycles relative to the start of the current Aeon, the YF scale has advantages when discussing the very distant geological or historic past.

Current year is 17,180 YF.