NEC3 Engineering and Construction Contract is the core document from which the options A-F are extracted. It contains all core clauses and secondary option clauses, together with the schedules of cost components and forms for contract data. Construction Clients' Board endorsement of NEC3 The Construction Clients' Board (formerly Public Sector Clients' Forum) recommends that public sector organisations use the NEC3 contracts when procuring construction. Standardising use of this comprehensive suite of contracts should help to deliver efficiencies across the public sector and promote behaviours in line with the principles of Achieving Excellence in Construction.