If n is invalid, the function returns an error. f (Optional) A time format string. If you do not include a value for f, the function uses the default time format H:MM:SS A. k (Optional) A locale identifier string that conforms to the locale naming standards. If you do not include a value for k, or if k is invalid, the function uses the ambient locale.The function returns a value of 0 if any of the following conditions are true:Insufficient information is provided to determine a unique time since the epoch (that is, any information regarding the time is missing or incomplete.The following expressions illustrate using the Num2GMTime function: