We are creating projects via Appropriation requests. The theory is that no commitments should be created before the project is released. However, we have proven that users can change the Res./Purc. indicator to 'immediate' before the project has been released. If the approver does not pick up that the project is not released yet, they can even create a Purchase order. 

You can not remove authorisation for the "immediate" indicator, because the indicator changes when you release the project from "from release" to "immediate".
    
How can we stop ANY committments from being created until the project has been released?

In OPSC make sure the Release immediately has been unmarked.
 
In transac OPUA (field selection network header) go to influencing choose network profile or controlling area depending on which you want to customize. Set the field "Reservation/Purc.req" CAUFVD-AUDISP make it to only displauy.
 
Go to transac OPUC (field selection network details) go to influencing, choose network profile or contolling area to which you want to customize the setting. Set it to change and in the field "Reservation/Purc.req" - AFVGD-AUDISP make it to only display. 
 
This would prevent the users from changing it to display when they create and assign activities to networks/projects. 

One more customization, in transac OPUU in the network tab make sure the setting is for 2 (from release)

or

A very effective way to handle this is using User status management .go to tcode bs02 and define a status profile which can be defaulted in the project profile, in the status profile define proj definition,WBS,network header and network activity as the infulenced object types.

Create a status "blck" as an initital status and in the business transaction field block PR and PRQ creation.
Next create a status"allw" which will be set after project is released and allow PR and PRQ creation after status is set

SAP PS Tips by : Pradeep, Ritesh 

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