Visual Conventions / Icons
Pyrocles
Posts: 2
On some newer equipment, on/off rocker switches are marked with a hyphen on one side and a circle on the other, while others have a hyphen on one side and nothing at all on the other. Since a hyphen could be a minus sign and a circle could be a zero, while nothing is vacancy, how does one decide which side is on and which is off? Wouldn't a minus and a plus (or a zero and a plus) be clearer? This matter is of major importance if the unit is misbehaving and one has to know whether the power is actually on.
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Comments
To answer your question, the modern power icon you are describing is actually a 0/1. It is Binary; 0= off = down on the switch, 1 = on = up on the switch. I have also seen manufacturers rotate this so that it is a circle and dash making the icons less intuitive, a huge mistake in my book.
This is a pretty basic modern User Interface paradigm that has taken hold throughout the industry [both pro and consumer] over the last few years.
There are many great books on the subject of User Interface Design, and how almost everything today has some sort of interface.
*edit - here is a good one:
The Design of Everyday Things: Donald A. Norman