(71)Strengthening the provisions concerning central purchasing bodies should in no way prevent the current practices of occasional joint procurement, i.e. less institutionalised and systematic common purchasing or the established practice of having recourse to service providers that prepare and manage procurement procedures on behalf and for the account of a contracting authority and under its instructions. On the contrary, certain features of joint procurement should be clarified because of the important role joint procurement may play, not least in connection with innovative projects. Joint procurement can take many different forms, ranging from coordinated procurement through the preparation of common technical specifications for works, supplies or services that will be procured by a number of contracting authorities, each conducting a separate procurement procedure, to situations where the contracting authorities concerned jointly conduct one procurement procedure either by acting together or by entrusting one contracting authority with the management of the procurement procedure on behalf of all contracting authorities. Where several contracting authorities are jointly conducting a procurement procedure, they should be jointly responsible for fulfilling their obligations under this Directive. However, where only parts of the procurement procedure are jointly conducted by the contracting authorities, joint responsibility should apply only to those parts of the procedure that have been carried out together. Each contracting authority should be solely responsible in respect of procedures or parts of procedures it conducts on its own, such as the awarding of a contract, the conclusion of a framework agreement, the operation of a dynamic purchasing system, the reopening of competition under a framework agreement or the determination of which of the economic operators party to a framework agreement shall perform a given task.