I have been told to modify the user exit "USEREXIT_SAVE_DOCUMENT_PREPARE"( MV50AFZ1), I don't have a access key for this. How can I include my program into this exit?
You must have the access key to modify the user exit. This is available from SSCR on SAPNet or OSS. Someone on your site must go into SAPNet or OSS, and register the the program for you, and give you the access key.
This was first published in April 2002