5.3 Where the Authority and the Project Company have agreed amendments to the service specifications, either the contract or the timetable will determine when the changes are made. Some soft services such as car parking and catering, may include an element of third party income and in some cases such income may have been underwritten as part of the base case financial model, or may be guaranteed to the relevant subcontractor by the Project Company. In such cases, Authorities will need to be assured that value testing does not result in any unintended transfer of demand or pricing risk back to the Authority.