Using this feature, you can restrict agreement document check-in and check out based on the Status Category and Status of the agreement. You can use the "Restrict Check-in of Documents" comply system property to restrict users from checking in and checking out agreement documents. By default, no value is available for the property, hence, no check-in restrictions will be applied.  For information, see Comply System Property. 

If you provide a Status Category as the property value, the check-in and check-out restrictions are applied to all the statuses belonging to that status category. If you provide a Status as the property value, the check-in and check-out restrictions are applied only to that status.

If an agreement Status Category or Status matches the property value and you check-out the document, all the options are disabled and you cannot check in the document. If an agreement Status Category or Status changes with the workflow and does not match the property value, the restrictions are removed and you can modify the agreement. 

Use Case

Consider the Restrict Check-in of Documents has In Authoring (Status Category) as the property value. When you open a document with the Internal Review status, the restriction will be applied and you cannot modify the document. This is because the restriction was applied at the Status Category level and all the statuses of that Status Category are considered for restriction.