The date [day,week,month,year] x1=d1=k1 is recurrence/repetition of the date [day,week,month,year] of the first event x2=d2, for the x3=k3'rd time, in system x3.
mekso unary operator: converts a string of digits which includes {pi} to the same string of digits without {pi}; if {pi} is not present in the original/input string, the output is identical