Text in force at CS27-10: from CS27-0, effective 14 Nov 2003.
(a) Each control and control system must operate with the ease, smoothness, and positiveness appropriate to its function.
(b) Each element of each flight control system must be designed, or distinctively and permanently marked, to minimise the probability of any incorrect assembly that could result in the malfunction of the system.
ED Decision 2003/015/RM · Source