this expression validates a date-time field in yyyy/m/d h:m:s or yyyy-m-d h:m:s format. The days are validated for the given month and year. Leap years are validated for all 4 digits years from 1600-9999, and all 2 digits years except 00.
Matches times seperated by either : or . will match a 24 hour time, or a 12 hour time with AM or PM specified. Allows 0-59 minutes, and 0-59 seconds. Seconds are not required.