OnValidate event handler

 [DataEventHandler(tableStr(TaxRegistrationNumbers_IN), DataEventType::ValidatedField)]
    public static void TaxRegistrationNumbers_IN_onValidatedField(Common sender, DataEventArgs e)
    {
        TaxRegistrationNumbers_IN TaxRegistrationNumbers_IN = sender as TaxRegistrationNumbers_IN; // Code to get the buffer
        boolean ret = true;
 
        ValidateFieldEventArgs args = e as ValidateFieldEventArgs; // Code to get args
 
        switch (args.parmFieldId())
        {
            case fieldNum(TaxRegistrationNumbers_IN, RegistrationNumber):
                {
                    if(strLen(TaxRegistrationNumbers_IN.RegistrationNumber) != 15)
                    {
                        ret = checkFailed("Registration number should be 15 characters"); // Just a validation to display on user interface
                    }
                }
                break;
        }
        args.parmValidateResult(ret);
    }