You don't have to be able to read the word ON to recognize it as a symbol. "Circle next to zigzag-thing" is as good as circle with line sticking out of it.

There's also precedent. Continental Europe standardized on "STOP" on stop signs back in the 70's, even though no continental language has "stop" in it.

Excuse me? No continental European language has the word stop in it? You should probably learn more languages before making claims like that.

Stop is a word in Dutch (the first recognisable use of the word I could find dates back to 1287). And German has stopf. I couldn't find a date for that, because my German isn't good enough to read their etymology dictionary, but it's source is Old High Germanic, so it's safe to say that stop has been around in continental Europe in Germanic languages since Medieval time at the very least.

Edit: A quick further Google search reveals that Norwegian and Danish (and thus most likely Sweden too) have the variation "stoppe" derived from Low German.

Seems a bit disingenuous to claim it was adopted despite "not being an existing word" if two languages use the exact rendering on the sign and 4 others use/have words that are so closely related that they have the same spelling, but 1 or 2 additional letters.

Further edit: French apparently adopted the word stop from English...in 1792

In Swedish it's "stopp".

https://en.wikipedia.org/wiki/Stop_sign#Stop_signs_around_th... shows examples of "Stop" used in Germany and Italy in the 1950s.

The German Wikipedia, at https://de.wikipedia.org/wiki/Stoppschild , gives an example of "stop" used in the Protectorate of Bohemia and Moravia (after the German occupation of Czechoslovakia) in 1939, though it says the sign was an imported variant.

https://en.wiktionary.org/wiki/stoppen#German points out:

> As in Dutch stoppen, the sense “to stop” is figurative from water flow being stopped by plugging. Only in this figurative meaning has the form been adopted into standard German proper, under the reinforcing influence of English to stop.

https://en.wiktionary.org/wiki/stop gives a list of continental European languages where 'stop' is part of the language. Nearly all borrow from the English. Not Dutch, however.

German stop signs used the word "HALT" before. My German dictionary defines "stopf" as darning yarn, and "stoppen" as stop. Not quite the same spelling. Typing "stop" into French Google translate autocompletes to "stoppé". I wouldn't be in the least surprised if the American spelling crept into many European languages as a result of the sign being ubiquitous for 41 years - it would be surprising if it didn't.

I wouldn't underestimate the influence on the language of the American occupation after the war, either, nor the global influence of American business since the war. English words have crept in everywhere.

But that symbol is in fact a "LOWPOWERMODETOGGLE" and that is a slightly more complicated than a circle broken by a line.

And everyone thought it was an on/off toggle.

Why is it easier to infer that 'O' means off than 'OFF' for a person who does not know any English?

Because it's a zero and the | is a one. Arabic numerals are more universal, and the convention of 0 for off and 1 for on was established precisely to avoid picking a language. Then the combined glyph for an on/off button was created, along with the similar broken circle glyph for on/standby. Those have squarish proportions, so the corresponding 0 and 1 glyphs are needed to match those proportions. Hence the four symbols now existing in Unicode (well, 3½)

> the convention of 0 for off and 1 for on was established precisely to avoid picking a language

I figured that politics was the case. What is less supportable is working backwards from that to concoct a rational reason. People who understand digital electronic conventions are highly unlikely to not recognize "ON" and "OFF". Furthermore, anyone who does not know either would find "ON" just as easy to learn as "|".

(That's why I referred to "ON" as a 'glyph'.)

We could also use "OHM" instead of Ω and "EUR" instead of €, but symbols provide more concise representations of meaning, especially in the case of a combined ON/OFF button. Much easier to fit the universal circle with 1 in it than "ON/OFF". The broken circle with 1 in it is way smaller than "ON/STANDBY". The other two symbols are then necessary to keep the proportions consistent across all four related glyphs.

That's the only argument I've seen for it that makes any sense. I'll counter by saying only "ON" is needed, not "ON/OFF", as the off part is implicit. Same goes for STANDBY.

This has been standard practice for a long time, I'm not just making things up on the fly. BTW, SBY is a standard abbreviation for STANDBY used by the military, if space is a problem. And SBY is a lot more google-able than an icon.

Yeah, all true. Especially the Google-ability of it.

Ok, here's my last argument then. It's aesthetically pleasing. I admit that's probably the weakest argument, but also the hardest to refute :)

It's not obvious that the "0" is a zero, as opposed to the letter "O" (cyrillic, latin) or the something entirely misleading, as this gesture: http://i.imgur.com/6KZ1nKG.jpg

I suspect the vertical slash | has as many lookalikes as the O, but I won't go there. I do want to mention that, as you demonstrated, the "1" that means on is more often represented as the Latin I or just a vertical stroke as in |, making it just as hard to ID as a numeral, especially if you don't know that the 1/0 are derived from the binary logic gates.

I would argue that the words "ON" and "OFF" when seen as glyphs are much less ambiguous than I/O.