(53)Contracting authorities should, except in certain specific situations, use electronic means of communication which are non-discriminatory, generally available and interoperable with the ICT products in general use and which do not restrict economic operators’ access to the procurement procedure. The use of such means of communication should also take accessibility for persons with disabilities into due account. It should be clarified that the obligation to use electronic means at all stages of the public procurement procedure would be appropriate neither where the use of electronic means would require specialised tools or file formats that are not generally available nor where the communications concerned could only be handled using specialised office equipment. Contracting authorities should therefore not be obliged to require the use of electronic means of communication in the submission process in certain cases, which should be listed exhaustively. This Directive stipulates that such cases should include situations which would require the use of specialised office equipment not generally available to the contracting authorities such as wide-format printers. In some procurement procedures the procurement documents might require the submission of a physical or scale model which cannot be submitted to the contracting authorities using electronic means. In such situations, the model should be transmitted to the contracting authorities by post or other suitable carrier. It should however be clarified that the use of other means of communication should be limited to those elements of the tender for which electronic means of communications are not required. It is appropriate to clarify that, where necessary for technical reasons, contracting authorities should be able to set a maximum limit to the size of the files that may be submitted.