II.2 ROLES AND RESPONSIBILITIES IN THE EVENT OF A JOINT TENDER  II.3 SEVERABILITY  II.4 PERFORMANCE OF THE CONTRACT  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 contract 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 contract.  This does not affect the legality, validity or enforceability of any other provisions of the contract, 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 contract must be interpreted as  if it had contained the substitute provision as from its entry into force.  II.4.1  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 contract, 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.4.2 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  2014/24/EU$^{18}$ and compliance with data protection obligations resulting from Regulation (EU)  2016/679 19 and Regulation (EU) 2018/1725 20 .  II.4.3  The contractor must obtain any permit or licence required in the State where the services are  to be provided. II.4.4  All periods specified in the contract are calculated in calendar days, unless otherwise specified. II.4.5  The contractor must not present itself as a representative of the contracting authority and must  inform third parties that it is not part of the European public service.  II.4.6  The contractor is responsible for the  personnel  who carry out the services and exercises its  authority over its  personnel  without interference by the contracting authority. The contractor  must inform its  personnel  that:  (a) they may not accept any direct instructions from the contracting authority; and  (b) their participation in providing the services does not result in any employment or  contractual relationship with the contracting authority.  18  OJ L 94 of 28.03.2014, p. 65  19  Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons  with regard to the processing of personal data and on the free movement of such data, and repealing Directive 95/46/EC  (General  Data  Protection  Regulation),  OJ  L  119,  4.5.2016,  https://eur-lex.europa.eu/legal- content/EN/TXT/PDF/?uri=CELEX:32016R0679&from=EN 20  Regulation (EU) 2018/1725 of the European Parliament and of the Council of 23 October 2018 on the protection of individuals  with regard to the processing of personal data by the Union institutions, bodies, offices and agencies and on the free movement  of such data and repealing Regulation (EC) No 45/2001 and Decision No 1247/2002/EC, OJ L 295/39 21.11.2018, https://eur- lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R1725&from=EN  16 