Every invitation to tender shall in particular ... prohibit any contact between the institution and tenderers save, by way of special exception, under the following conditions ... after the tenders have been opened and at the instance of the departments of the institution, if some clarification is required in connection with a tender, or if obvious clerical errors contained in the tender must be corrected, the institution may contact the tenderer.
... if the departments of the institution notice an error, a lack of precision, an omission or any other type of clerical defect in the text of the invitation to tender, they may, in a manner identical with that applicable in respect of the original invitation to tender, inform the persons concerned accordingly ...