(58)While essential elements of a procurement procedure such as the procurement documents, requests for participation, confirmation of interest and tenders should always be made in writing, oral communication with economic operators should otherwise continue to be possible, provided that its content is documented to a sufficient degree. This is necessary to ensure an adequate level of transparency that allows for a verification of whether the principle of equal treatment has been adhered to. In particular, it is essential that oral communications with tenderers which could have an impact on the content and assessment of the tenders be documented to a sufficient extent and by appropriate means, such as written or audio records or summaries of the main elements of the communication.