The first paragraph of clause 4.1 in the Yellow and Silver Books deals with the design-build Contractor's fitness for purpose obligation. As with other contracts, the FIDIC forms require the Contractor to provide a performance security in order to secure his proper performance of the Contract. Clause 4.3 in the 2017 Books contains requirements as to the Representative's qualifications, experience and competence and provides for the Engineer's or Employer's consent to the person whom the Contractor proposes to appoint as his Representative. The 2017 Red Book deals with nominated subcontractors in clause 5.2 in the same terms as clause 4.5 of the other two Books. The 2017 contracts cover nominated subcontractors in much more detail than the 1999 editions and provide important protections. Clause 4.4.1 of the 2017 Red Book sets out a procedure for review of the Contractor's documents by the Engineer.