calendar-mark-date-pattern

calendar-mark-date-pattern is a compiled Lisp function in `diary-lib.el'.

(calendar-mark-date-pattern MONTH DAY YEAR &optional COLOR)

Mark all dates in the calendar window that conform to MONTH/DAY/YEAR.
A value of 0 in any position is a wildcard. Optional argument COLOR is
passed to `calendar-mark-visible-date' as MARK.