Section 1605.16 - Signal Systems(a) Hoisting machines shall be operated in response to manual signals, telephone communications, or to a visible or audible code signal. Any of these may be used separately or in combination. Refer to Section 1605.21.(b) Operators and signalmen shall be able to comprehend signals readily and to execute them properly. Refer to Section 1605.21.Cal. Code Regs. Tit. 8, § 1605.16