(68)New electronic purchasing techniques are constantly being developed, such as electronic catalogues. Electronic catalogues are a format for the presentation and organisation of information in a manner that is common to all the participating bidders and which lends itself to electronic treatment. An example could be tenders presented in the form of a spreadsheet. Contracting authorities should be able to require electronic catalogues in all available procedures where the use of electronic means of communication is required. Electronic catalogues help to increase competition and streamline public purchasing, particularly in terms of savings in time and money. Certain rules should however be laid down to ensure that the use of the new techniques complies with this Directive and with the principles of equal treatment, non-discrimination and transparency. Thus, the use of electronic catalogues for the presentation of tenders should not entail the possibility of economic operators limiting themselves to the transmission of their general catalogue. Economic operators should still have to adapt their general catalogues in view of the specific procurement procedure. Such adaptation ensures that the catalogue that is transmitted in response to a given procurement procedure contains only products, works or services that the economic operators estimated - after an active examination - correspond to the requirements of the contracting authority. In so doing, economic operators should be allowed to copy information contained in their general catalogue, but they should not be allowed to submit the general catalogue as such. Furthermore, where sufficient guarantees are offered in respect of ensuring traceability, equal treatment and predictability, contracting authorities should be allowed to generate tenders in relation to specific purchases on the basis of previously transmitted electronic catalogues, in particular where competition has been reopened under a framework agreement or where a dynamic purchasing system is being used. Where tenders have been generated by the contracting authority, the economic operator concerned should be given the possibility to verify that the tender thus constituted by the contracting authority does not contain any material errors. Where material errors are present, the economic operator should not be bound by the tender generated by the contracting authority unless the error is corrected. In line with the requirements of the rules for electronic means of communication, contracting authorities should avoid unjustified obstacles to economic operators’ access to procurement procedures in which tenders are to be presented in the form of electronic catalogues and which guarantee compliance with the general principles of non-discrimination and equal treatment.