How to Find User Exits for SAP Program or Transaction Code

ABAP developer can find a list of user exits used for any SAP program or transaction code using SMOD transaction.

If you know the program name, launch SE38 and check the package name that the program is created in.
Actually there are numerous ways to learn the program name or the transaction code for a program that is running on SAP GUI.

For example, if you launch SAP VA01 transaction code of Order Entry screen, by using the SAP GUI tray on the bottom right of the screen.

ABAP program name and SAP transaction code on a SAP GUI screen

Or launch SE93 Maintain Transaction tcode and type the transaction name, VA01 and press Display F7 button.

ABAP package name for any SAP transaction code on SE93

If you know the ABAP program name, launch SE38 and type the program name, select "Attributes" option.

display ABAP program attributes

Then press Display button.

SAP package name of any ABAP program

After we have the ABAP package name VA for the SAP program SAPMV45A or transaction code VA01, launch SMOD transaction.

Click on Enhancement input box, then press F4

use SMOD transaction for ABAP user exits on SAP program

When "Input Help Personal Value List" popup screen is displayed, click on Information System button.

ABAP enhancements list on SMOD tcode

In Package textbox, type the name of the ABAP package that the program is created in.
Then run the filter.

SAP Repository Info System for ABAP enhancements list

A list of user exits created for the related ABAP package is listed as a result.
I marked the user exists that are related with ABAP program SAPMV45A. You can filter the list for the target user exit by comparing the names and using the description of the user exit.

ABAP user exits list for sales order package

For example, you think V45A0001 is related for your requirement.
Double-click on it.

When you are back on SMOD initial screen with Enhancement set for V45A0001, select Components option and press Display or F7

SAP enhancements list for Order Entry transaction

As you see in below screenshot, only one function module exit named EXIT_SAPFV45S_001 is defined for use of ABAP programmers for the enhancement project V45A0001

ABAP user exit for SAP order entry transaction

Double click on the function module name display ABAP source code for the FM EXIT_SAPFV45S_001 (User Exit Product Selection)

As seen below the function module code has only an Include statement as follows

INCLUDE ZXVVAU02.

ABAP function module exit

ABAP developers can add their custom codes in provided include ZXVVAU02 without changing the function module EXIT_SAPFV45S_001 code.