6.6. Service providers will often be party to interface arrangements with other sub-contractors on the project (e.g. the construction sub-contractor and other service providers) or between the soft service providers or other contracts. The bid and transfer arrangements will need to cover any new contractor's entry into these interface arrangements. Although these are not part of the services actually being tested, they are a necessary part of the process of inserting the new contractor into the project. The public sector client should, at the outset of the PPP transaction and as part of its due diligence process, ensure that the relevant interface agreements have 'Deeds of Accession' attached to them. Failure to have such mechanisms in place could undermine the market test.