Power Supply On Off Switch Symbol

Some older devices instead have a power switch that accomplishes the same thing as a hard power button.
Power supply on off switch symbol. O means the power is off and means the power is on. The switch does not fully disconnect the device from its power supply this may appear on a toggle switch opposite a power on symbol alone on a pushbutton that places the device into a standby state or alone on a button that switches between on and standby. To turn the power washer on press the down on the power switch. Why is this important.
I know i line and o circle symbols are used to specify a switch that turn on and off the power supply. Iec 5010 the power on off symbol line within a circle is used on buttons that switch a device between on and fully off states. On off power button symbols i o. Iec 5009 the standby symbol line partially within a broken circle indicates a sleep mode or low power state.
My question is what is its origin. Because it means that devices with that broken o symbol are not truly off until they are unplugged. They are the international symbols for power on and power off. Iec 60417 5009 the standby symbol line partially within a broken circle indicates a sleep mode or low power state.
The power switch is a rocker switch and it has two symbols on the face. The power switch on the back of the case is actually for the power supply installed in the computer. Because i thought that it represent a power line that can be plugged on symbol and a closed line and thus without power supply but seen that in wikipedia said that it can come from 1 and 0 used in binary to represent on and off bits i don t know. To turn the power washer off press.