Field help (KAUZUSR) 

This field is used to limit the acceptance rights for a return requested by a user. This limitation depends on the assignment of the SAUZRET user parameter which determines whether users can modify a return for which they are not the authorized operator.
By default the user code proposed is the code of the current user performing the entry. If no user is specified, all operators can modify the return.
SEEINFO Once the return is saved, this information can no longer be modified.