See IEC 73.Clause 4.3 (in my 1991 version) indicated blue is for "mandatory significance", while white, gray and black are listed as "no specific meaning assigned." Clause 6 elaborates: BLUE actuator means Mandatory: Condition which requires action, such as a reset function.
This standard only assigns meaning to red, yellow, green, and blue. It states that white, gray and black have no intrinsic meaning, and avoids mentioning other colors. Exact color definitions (hue, saturation) are defined in ISO 3865, "Safety colours and safety signs". You may argue that the standard is not mandatory for your application. I've fought several battles over these requirements, and lost more than I've won. ---------- Subject: Color-Coded Function Keys . . . We have a customer insisting that the CE requirements require these function keys to be "grey". Ours are "blue". . .
