The validity period of the tender, during which tenderers may not modify the terms of their tenders  in any respect, is indicated under Heading IV.2.6 of the contract notice. Submission of a tender implies acceptance of all the terms and conditions set out in the procurement  documents and, where appropriate, waiver of the tenderer's own general or specific terms and  conditions. The submitted tender is binding on the tenderer to whom the contract is awarded for the  duration of the contract.  Contacts between the contracting authority and tenderers are prohibited throughout the procedure  save in exceptional circumstances and under the following conditions only:  Upon request, the contracting authority may provide additional information solely for the purpose of  clarifying the procurement documents.  Any request for additional information must be made in writing only through the above TED e- Tendering website in the "Questions & answers" tab, by clicking "Create a question" (registration on  TED e-Tendering is required to be able to create and submit a question).  The contracting authority is not bound to reply to requests for additional information received less  than six working$^{7}$ days before the time-limit for receipt of tenders. The contracting authority may, on its own initiative, inform interested parties of any error, inaccuracy,  omission or any other type of clerical error in the text of the procurement documents.  Any additional information will be published on the above TED e-Tendering website. The website will  be updated regularly and it is the economic operator's responsibility to check for updates and  modifications during the submission period$^{1}$. Tenders will be opened in public at the time and place indicated under Heading IV.2.7 of the contract  notice. A maximum of one representative per tender may attend the opening session. For  organisational and security reasons the tenderer must provide the full name, date of birth, nationality  and ID or passport number of the representative at least two working days in advance to:  procurement@enisa.europa.eu. The representative will be required to present the submission  receipt generated by e-Submission and to sign an attendance sheet. The contracting authority  reserves the right to refuse access to its premises if the above information or the submission receipt  are not provided as required. The public part of the opening session will be strictly limited to the following aspects:  - verification that each tender has been submitted in accordance with the submission requirements  of the call for tender;  $^{7}$ Working days at the contracting authority's location indicated under Heading I.1 of the contract notice.  Page  3  of  5 3.2 Opening of tenders  3.1 Submission phase (before the time-limit for receipt of tenders)  3. Contacts during the procurement procedure. 