How to create derived role and When to use it ?

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http://sap-securityguide.com/how-to-create-derived-role-and-when-to-use-it/#more-264

There are 2 possible reasons to use derive role method ( deriving a role authorization from an existing role)

●      The role menus are identical but the authorizations for the menu actions are different in the derived role.

●      The menu and authorizations of the derived role are identical, but the organizational levels are different in the derived role.

Step by step to create derived role

1.      Create a single role that will use as a template .

2.      Enter a role description text.

3.      Enter the name of the role from which all transactions including the menu structure are to be copied in the Derive from role field in the Description tab page.

create derived role

4.      Save to create a role whose menu was derived from another role.

If there are additional transaction codes added to the menu of the original role, they are copied into the derived role.

Step by step to Copying the Authorizations of the Original Role to the Derived Role

1.     Made change in the original role from which the authorizations are to be derived.

2.      Click on generate derived role button to copy authorization to derived role.

**Remarks ***

The organization level data is only copied the first time the authorization data is adjusted for the derived role. If data is maintained for the organizational levels in the derived role,  and if you have maintained the organizational levels using the dialog box, the data is not overwritten by another conciliation (See more detail in  SAP Note 314513).