1.4.3 Services  1.5 Place of performance: where will the contract be performed?  1.6 Nature of the contract: how will the contract be  implemented?  A) Cascade mechanism: Please refer to sections 3 and 4 of Annex 1  “ Technical Specifications ” for a detailed  description of the requested services and to section 6.3 for the acceptance procedures.  The services will be performed at the contractor's premises and/or at  ECHA’s  premises in  Helsinki (for the exact location see section 9.3 of Annex 1  “ Technical Specifications ” ).  The procedure will result in the conclusion of multiple Framework Contracts with several  economic operators, as described below.  A framework contract establishes a mechanism for future repetitive purchases by the  Contracting Authority  to be awarded in the form of specific contracts. The signature of a  framework contract does not impose an obligation on the  Contracting Authority to  conclude specific contracts with a framework contractor. Specific contracts shall be awarded on the basis of the terms laid down in the framework  contract, refined or, in duly justified circumstances, supplemented to reflect the  particular circumstances of the specific contract. The different types of specific contracts  are set out in section 6 of Annex 1  “ Technical Specifications ”. Tenderers need to take full account of the full set of procurement documents, including  the provisions of the draft framework contract and of the Service Level Agreement, as  the procurement documents will define and govern the contractual relationship(s) to be  established between the  Contracting Authority and the successful tenderers. Special  attention is to be paid to the provisions specifying the rights and obligations of the  contractor, in particular those on payments, performance of the contract, confidentiality,  and checks and audits. In  Lot 1 the procedure will result in the conclusion of multiple framework contracts  (FWC) in cascade and with reopening of competition under certain circumstances. The FWC will be concluded in the form of separate, but identical, contracts with a  maximum number of 3 (three) contractors provided that there are enough tenderers  that have access to the procurement, are not excluded, satisfy the selection and award  criteria, and comply with the Tender Specifications. The tenders deemed admissible as a result of the evaluation will be ranked in descending  order to establish a list of contractors and a sequence in which they will be offered  specific contracts during the implementation of the FWC. The modalities of  implementation of the FWC will be as follows:  The cascade of contractors will be used for specific contracts. In certain below defined  circumstances the 3 contractors will be invited to compete in a reopening of competition  mode. 7