Returns TRUE if the weekday is valid. The seven GDateWeekday enumeration values are the only valid weekdays.
weekday
TRUE if the weekday is valid [5] For the purposes of this function, leap year is every year divisible by 4 unless that year is divisible by 100. If it is divisible by 100 it would be a leap year only if that year is also divisible by 400.
See Implementation
Returns TRUE if the weekday is valid. The seven GDateWeekday enumeration values are the only valid weekdays.