ma'irdeidetri lujvo

x1 (number) is the date/day notation of the month of event/state x2, in system x3.

masti zei djedi zei detri. As default, the number x1 is counted from the first day of the month. See de'i'o for BAI. See also detke'u.

In notes:

de'i'o (exp!)
on the Nth day of the month.