How to separate park and post role in Post and park can be performed within same T-Code: FV50, FV60, FV70 and FBV0?

When you execute the T-code: FV50, FV60, FV70 or FBV0, you can find the Post and Park button.

The logic and design purpose for this behavior is as following:

1. User who is authorized to post is also authorized to change since in the organizational aspect, it is usually given to higher authority and changes can possibly be made before the point of final posting. Therefore the activity to post and change cannot be segregated. 
2. The logic is that the authorization to post is higher than the authorization to park. Therefore the individual who is authorized to post will also automatically be assign authorization to park. 
3. Once other single roles are added to the composite role which have other financial transactions such as G/L account clear (e.g. F-03, F-44), the user will see a post button on the screen of T-code: FV60. Authorization for activity 0 automatically allows parked document posting to occur.

Some workaround or solution to change current system process.

Possible workarounds could be:

1. Set up a validation to prevent a users from posting/parking; 
2. Use workflow to release the park documents; 
3. Set up variant transactions excluding either the posting or the parking button and give the users authority for one variant transaction only; 
4. Use the exit provided by SAP note 361420 to deactivate the posting/parking button depending on users.

Also you could check the configuration for role setting:

  1.   If you want to restrict the authorization only to the activity “PARK”, you can do this by assigning activity 77 (park) to the relevant authorization object. 

  2.   You cannot restrict the authorization only to the activity “POST” (save as complete) as this requires also activity 01 (and this cannot be given without 77).

For more information you could check following SAP KBAs.

1886315

1885677

1885760

1901585

1901507