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Difference Between SY-UCOMM and OK_CODE

Updated Feb 14, 2024

In SAP ABAP programming, understanding the differences between system fields like SY-UCOMM and OK_CODE is crucial for efficient development. While both serve similar purposes, they are utilized in different contexts and require distinct handling. Here in this tutorial, we will learn about the difference Between SY-UCOMM and OK_CODE in the SAP system.

The SY-UCOMM field is utilized to execute functions that the user intends to perform during a specific event. It is commonly employed in menus and similar contexts, particularly in conjunction with <pfstatus>.

On the other hand, OK_CODE is typically employed within screens. You define the function within the screen itself and subsequently utilize it within the main program.

OK_CODE essentially serves as a temporary storage for the value of SY-UCOMM.

During user interactions with screen elements, the function code you've assigned is populated into the SY-UCOMM field, which in turn is reflected in OK_CODE.

In your ABAP programs, it's advisable to work with the OK_CODE field instead of SY-UCOMM for two primary reasons: Firstly, the ABAP program retains full control over its declared fields, and secondly, altering the value of an ABAP system field is not recommended. However, it's imperative to always initialize the OK_CODE field within an ABAP program for the following reason:

Just as the OK_CODE field in the ABAP program and the system field SY-UCOMM receive the contents of corresponding screen fields during the PAI event, their contents are also assigned to the OK_CODE screen field and the system field SYST-UCOMM during the PBO event. Consequently, it's crucial to clear the OK_CODE field within the ABAP program to ensure that the function code of a screen isn't inadvertently filled during the PBO event with an unwanted value.

This becomes particularly significant when the subsequent PAI event might be triggered with an empty function code, such as when using ENTER. Empty function codes do not impact SY-UCOMM or the OK_CODE field, hence retaining old field contents during transport.


Purpose Executes user-requested functions during events Utilized within screens, defines functions within screen and used in the main program
Usage Typically used in menus and similar contexts Commonly employed within screens
Initialization Automatically populated during user interaction Must be explicitly defined and initialized within the screen or program
Control Managed by the ABAP system Retains full control within the ABAP program
Altering Value Not recommended Acceptable practice within the program
Relationship Reflects the function code assigned by the user in SY-UCOMM Stores the temporary value of SY-UCOMM
Clearing in PBO Event Not necessary Crucial to clear to avoid unintended values in subsequent PAI events
Impact on Empty Function Codes Affected by empty function codes Does not impact, ensuring old field co