STD.Date.IsValidTime STD.Date.IsValidTime Date.IsValidTime ( time ) time A time value in the Time_t format. Return: IsValidTime returns a BOOLEAN value. The IsValidDate function returns TRUE if the time is valid, by validating each of the individual components (hours, minutes, and seconds).. Example: IMPORT STD; d1 := 19631122; d2 := 19990230; firstTest := STD.Date.IsValidDate(d1); //d1 is valid secondTest := STD.Date.IsValidDate(d2); //d2 is not valid