(121)The evaluation has shown that there is still considerable room for improvement in the application of the Union public procurement rules. With a view to a more efficient and consistent application of the rules, it is essential to get a good overview on possible structural problems and general patterns in national procurement policies, in order to address possible problems in a more targeted way. That overview should be gained through appropriate monitoring, the results of which should be regularly published, in order to allow an informed debate on possible improvements of procurement rules and practice. Acquiring such a good overview could also allow insights on the application of public procurement rules in the context of the implementation of projects co-financed by the Union. Member States should remain free to decide how and by whom this monitoring should be carried out in practice; in so doing, they should also remain free to decide whether the monitoring should be based on a sample-based ex-post control or on a systematic, ex-ante control of public procurement procedures covered by this Directive. It should be possible to bring potential problems to the attention of the proper bodies; this should not necessarily require that those having performed the monitoring have standing before courts and tribunals. Better guidance, information and support to contracting authorities and economic operators could also greatly contribute to enhancing the efficiency of public procurement, through better knowledge, increased legal certainty and professionalisation of procurement practices. Such guidance should be made available to contracting authorities and economic operators wherever it appears necessary to improve correct application of the rules. The guidance to be provided could cover all matters relevant to public procurement, such as acquisition planning, procedures, choice of techniques and instruments and good practices in the conduct of the procedures. With regard to legal questions, guidance should not necessarily amount to a complete legal analysis of the issues concerned; it could be limited to a general indication of the elements that should be taken into consideration for the subsequent detailed analysis of the questions, for instance by pointing to case-law that could be relevant or to guidance notes or other sources having examined the specific question concerned.