Like some of its predecessors, this chapter is concerned with selected aspects of the system that it considers. Nominated sub-contracts have been introduced and the standard documents listed in Chapter 4. They may be used within some JCT main contracts for which the architect provides the design under direct appointment by the employer and in which the contractor and all his sub-contractors, domestic and nominated, construct the works in accordance with that design. It is, however, possible to arrange for a nominated sub-contractor to design his own work in whole or part and to be responsible to the employer for this design, rather as when performance specified work is included in the contract for the contractor to price directly and for which he assumes responsibility over the design (see Ch. 17). However, as is noted hereafter, there is not the same detail in the provisions over this as occurs for performance specified work and the matter is approached contractually rather differently.