In the event of a joint tender submitted by a group of economic operators and where the group does  not have legal personality or legal capacity, one member of the group is appointed as leader of the  group. Each provision of this FWC is severable and distinct from the others. If a provision is or becomes  illegal, invalid or unenforceable to any extent, it must be severed from the remainder of the FWC. This  does not affect the legality, validity or enforceability of any other provisions of the FWC, which continue  in full force and effect. The illegal, invalid or unenforceable provision must be replaced by a legal, valid  and enforceable substitute provision which corresponds as closely as possible with the actual intent of  the parties under the illegal, invalid or unenforceable provision. The replacement of such a provision  must be made in accordance with Article II.11. The FWC must be interpreted as if it had contained  the substitute provision as from its entry into force.  II.4.1  Signature of the FWC does not guarantee any actual purchase. The contracting authority is  bound only by specific contracts implementing the FWC.  II.4.2  The contractor must provide services of high-quality standards, in accordance with the state of  the art in the industry and the provisions of this FWC, in particular the tender specifications  and the terms of its tender. Where the Contracting Authority has the right to make  modifications to the results, they must be delivered in a format and with the necessary  information which effectively allow such modifications to be made in a convenient manner.  II.4.3  The contractor must comply with the minimum requirements provided for in the tender  specifications. This includes compliance with applicable obligations under environmental, social  and labour law established by Union law, national law and collective agreements or by the  international environmental, social and labour law provisions listed in Annex X to Directive  17  II.3 SEVERABILITY  II.4 PROVISION OF SERVICES  II.2 ROLES AND RESPONSIBILITIES IN THE EVENT OF A JOINT TENDER  ‘ Request for services’ : a document from the contracting authority requesting that the contractors  in a multiple FWC with re-opening of competition provide a specific tender for services whose terms  are not entirely defined under the FWC; ‘ Result ’ : any intended outcome of the  Implementation of the FWC , whatever its form or nature. A  Result  may be further defined in this FWC as a deliverable. A  Result  may, in addition to newly created  materials produced specifically for the contracting authority by the contractor or at its request, also  include  Pre-existing materials ; ‘ Specific contract’ : a contract implementing the FWC and specifying details of a service to be  provided;  ‘ Supplier portal’ : the  e-PRIOR  portal, which allows the contractor to exchange electronic business  documents, such as invoices, through a graphical user interface; its main features can be found in the  supplier  portal  overview  document  available  on:  http://ec.europa.eu/dgs/informatics/supplier_portal/doc/um_supplier_portal_overview.pdf