Creation of function module for updating the ztable

Question

Hi,
I am sending the requirement for ceation of function module for updating the ztable.
Requirement----
Table Updation rule (New record)
While creating a new record the calling function will export the following to the table handling function.
Table field     Probable Values
ZORDERNO------->     Sales Delivery no in case of sales orderShipment no in case of transfer order
UNAME----
>     User ID
ZORDTYPE----
>     SALEOR in case of sales orderTRANSF in case of transfer order
ZREFDOCNO----
>Sales Order no in case of sales orderPurchase Order no in case of transfer order
ZREFDOCNO1----
>Delivery no in case of transfer order
The table handling function will calculate the following fields
Table field     Probable Values
ZREQNO----
>Running serial number (incremented by 1 for each new record)
ZREQDAT     -
>System date
ZREQTIME----
>     System time
ZSTATUS----
>OPEN (for all new records)
Before inserting a new record the table handling function will always check if a previous record exists for the same order / shipment no. if record exists the function will not insert a new record.
Table Updation rule (Status Update)
While updating a record the calling function will export the following to the table handling function.
Table field     Probable Values
ZORDERNO----
>Sales order no in case of sales orderShipment no in case of transfer order
ZSTATUS----
>CANCEL if cancellation successfulERROR if cancellation not possible (order already processed)
The table handling function will calculate the following fields
Table field     Probable Values
ZSTATDAT----
>System date
ZSTATTIME----
>     System time

Answer 1

Do you have to create/update new record in Ztable through Function Module ?
or you need to write FM only for validation?
Any how, you need to create a Program with Input values for the fields of Ztable, and for rest of fields the Value can be calculated based on input as per your requirement.
Let me know clearly what exactly u need ?
Regards,
Kiran