Model version of 31-08-2020 All costs incurred for the preparation and submission of requests to participate or tenders are  to be borne by the candidates or tenderers and will not be reimbursed. This invitation is in no way binding on the contracting authority. The contracting authority's  contractual obligation commences only when the contract with the successful tenderer is  signed by both parties.  Up to the signature of the contract the contracting authority may cancel the procurement  procedure without candidates or tenderers being entitled to claim any compensation. Any  such decision must be substantiated and candidates or tenderers notified.  The validity period of the tender, during which tenderers may not unilaterally modify the  terms of their tenders in any respect, is indicated under Heading IV.2.6 of the contract notice. Submission of a request to participate/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 candidates or 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  eTendering website 1 in the "Questions & answers" tab, by clicking "Create a question"  (registration on TED eTendering is required to be able to create and submit a question).  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 eTendering 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. The opening of the received requests to participate is not public.  Once the contracting authority has opened the requests to participate, they shall become its  property and will be treated confidentially.  2  3.2 Opening of requests to participate 3.1 Submission of requests to participate phase 3. Contacts during the procurement procedure.  2. Legal effects of the invitation to tender and submission of a request to  participate/tender. 