This function validates the entries in the fields of the orders
        screen record.
Function order_validate (orders.4gl):
01 FUNCTION order_validate(d)
02   DEFINE d ui.Dialog 
03   IF NOT d.getFieldTouched("orders.*") THEN
04      RETURN TRUE
05   END IF
06   IF d.validate("orders.*") < 0 THEN
07      RETURN FALSE
08   END IF
09   IF NOT order_check_store_num() THEN
10      RETURN FALSE
11   END IF
12   RETURN TRUE
13 END FUNCTION
Note: 
- Line 01 The dialog object is passed to this function,
                    allowing the use of methods of the DIALOG class.
 
- Lines 03 thru 05 return TRUE to the calling function if the
                    fields in the orders record have not been touched.
 
- Lines 06 thru 08 call the validate() method of the dialog
                    object to execute any NOT NULL, REQUIRED, and
                        INCLUDE validation rules defined in the form specification
                    file for the fields in the orders screen record. If this
                    validation fails, FALSE is returned to the calling
                    function.
 
- Lines 09 thru11 call the order_check_store_num function to
                    verify that the store_num value exists in the
                        customer database table. If this validation fails,
                        FALSE is returned to the calling function.
 
- Line 12 returns TRUE to the calling
                    function when the validation is successful.