(60)The instrument of framework agreements has been widely used and is considered as an efficient procurement technique throughout Europe. It should therefore be maintained largely as it is. However, certain aspects need to be clarified, in particular that framework agreements should not be used by contracting authorities which are not identified in them. For that purpose, the contracting authorities that are parties to a specific framework agreement from the outset should be clearly indicated, either by name or by other means, such as a reference to a given category of contracting authorities within a clearly delimited geographical area, so that the contracting authorities concerned can be easily and unequivocally identified. Likewise, a framework agreement should not be open to entry of new economic operators once it has been concluded. This implies for instance that where a central purchasing body uses an overall register of the contracting authorities or categories thereof, such as the local authorities in a given geographical area, that are entitled to have recourse to framework agreements it concludes, that central purchasing body should do so in a way that makes it possible to verify not only the identity of the contracting authority concerned but also the date from which it acquires the right to have recourse to the framework agreement concluded by the central purchasing body as that date determines which specific framework agreements that contracting authority should be allowed to use.