Userexits allow us to add our own functionality to SAP standard program without modifying it . These are implemented in the form of subroutines and hence are also known as FORM EXITs. The userexits are generally collected in includes, and attached to the standard program by the SAP.
All Userexits start with the word USEREXIT_...
The problem lies in finding the correct userexit and how to find it if one exists for the purpose. Once the correct userexit is found, the necessary customer code is inserted in the customer include starting with the z..
in the form routine.
Certain application like SD still provide this form of enhancement using userexit but this practice is no longer being followed for newer extensions
instead they are using EXITs which come bundeled in enhancement packages . Neverthiless existing USEREXITS will be supported by SAP an all the newer versions of SAP.
HOW TO FIND USEREXITS
Userexits can be found in number of ways:
1) To find userexits in SD module , goto object navigator(SE80) and select
development class from the list and enter VMOD in it. All of the userexits in SD are contained in the development class VMOD. Press
enter and you will find all the includes which contain userexits in SD for
different functions like PRICING, ORDER PROCESSING etc. Select the userexit according to the requirement and read the comment inserted in it
and start coding .
In 4.6c, you can use "RSMODPRF" program to create field exits.
An example of a user exits :-
MODULE user_exit_0001 INPUT
WHEN 'BACK OR EXIT'.
SET SCREEN 0.
Note that you can write any code that satisfy your needs. ****
But in this case, this was wrote as a sample code for reference sake. ****
And you can test it. ****
SET SCREEN 100.
hope this will give you an idea of what you are looking for ..
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