The No Symbol: The History of the Red Circle-Slash | Hacker News Reader

The No Symbol: The History of the Red Circle-Slash

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Wikipedia calls it the "No Symbol" [0]. ISO 7010 calls it the "prohibition sign" [1]. In Unicode, it's available as a combining character with the practical name "COMBINING ENCLOSING CIRCLE BACKSLASH" (U+20E0) [2] and in emoji form it's the "NO ENTRY SIGN" (U+1F6AB) [3].

0: https://en.wikipedia.org/wiki/No_symbol

1: https://en.wikipedia.org/wiki/ISO_7010

2: https://www.compart.com/en/unicode/U+20E0

3: https://www.compart.com/en/unicode/U+1F6AB

> Wikipedia calls it the "No Symbol" [0]. ISO 7010 calls it the "prohibition sign" [1].

“Circle-bar” to my mind is the most eloquent and evocative of the names I’ve seen for this symbol.

I can’t remember where I heard/read “circle-bar” which was many many years ago.

"Slashed circle" is the most succinct description I can come up with. To me, "bar" suggests a horizontal line, like a capital-Theta Θ

yes, the "do not enter" sign is a circle and bar

No entry should be a red circle background with horizontal white bar across the centre.

That’s U+26D4: https://www.compart.com/en/unicode/U+26D4

U+1F6AB is for roundtrip compatibility with the Japanese KDDI emoji set (#31 here: http://emoji.digital/kddi-au/).

Those date from 1993 and 2010. There's also U+26D4 NO ENTRY (2009) and U+1F6C7 PROHIBITED SIGN (2014). I wonder what the history is that we ended up with four different code points for a similar concept.

I included just the ones that were the same visual representation, U+26D4 is a different symbol. The glyph for U+1F6C7 seems to be missing in most places, I can't find an authoritative representation of it to confirm it's the same visual symbol.

EDIT: Looks like U+1F6C7 "PROHIBITED SIGN" is indeed the same symbol, as seen in the Unicode 7.0 charts [0]

0: https://www.unicode.org/charts/PDF/Unicode-7.0/U70-1F680.pdf

> I included just the ones that were the same visual representation, U+26D4 is a different symbol. The glyph for U+1F6C7 seems to be missing in most places, I can't find an authoritative representation of it to confirm it's the same visual symbol.

I don't think that there's any meaningful sense in which two Unicode code points may be said to have, or not have, the same symbol, except in reference to a particular font. The standard just indicates some possibilities:

> The shapes of the reference glyphs used in these code charts are not prescriptive. Considerable variation is to be expected in actual fonts. The particular fonts used in these charts were provided to the Unicode Consortium by a number of different font designers, who own the rights to the fonts.

Sure, but the topic at hand here is not unicode code points, but a particular visual symbol.

And yet we still needed to do Han unification. Unicode is ridiculous at this point.

To be fair, two of the four discussed here (U+1F6AB and U+1F6C7) are early "astral plane" emoji just after Unicode gave up on Han unification as a plan and moved back to trying to better round-trip existing encodings. The existence of emoji in general is partly Unicode's mea culpa for attempting Han unification in the first place.

(It was an odd sort of apology, given most of the damage was already done and the astral plane should have probably opened up a lot sooner in hindsight, but it was a fascinating sort of apology in the way that emoji has done more for Unicode acceptance testing in first-language-English developed applications than just about any other block in Unicode history.)

Was hoping the article might shed some light on the ambiguity of some of the prohibition signs in the UK and parts of Europe, e.g. the "no motor vehicles" sign[0]. Given that the ones with the red circle but without the red slash typically mean up to what is shown is allowed and anything above is not (e.g. maximum speed, maximum width, maximum height), the one showing a car and a motorbike could reasonably be interpreted as anything up to the size of a motorbike and car are allowed but anything bigger (such as a lorry and a bus) are not. Adding a simple slash, as the rest of the world seems to do, and as per other prohibition signs in the UK and Europe (e.g. no right turn) would remove all ambiguity. Wonder if there's some strange history behind that apparent anomaly.

[0] https://en.wikipedia.org/wiki/Prohibitory_traffic_sign#No_mo...

I always thought the slashed ones were ambiguous, as adding a slash on top of a red circle which already signifies prohibition could be interpreted as a double negation.

> that the ones with the red circle but without the red slash typically mean up to what is shown is allowed and anything above is not (e.g. maximum speed, maximum width, maximum height)

These number are limits on a continuous domain, where inclusion or exclusion of the limit number itself is basically meaningless. The list of vehicles is a set (without necessarily a clear order) which has fundamentally different properties so it's not surprising the meaning is slightly different. You couldn't have a sign that forbids pedestrians and cars but allows motor vehicles otherwise.

The rules are simply that when a red on white sign displays anything other than a number (with or without a slash) it means this thing is forbidden. If it's a number it means a high limit.

Back in the days when the League of Nations was deciding all this, there was a road sign in the German Empire consisting of a red circle around a white background with a black arrow pointing straight ahead (and no slash). This did not mean it's forbidden to go straight ahead, it meant it's _mandatory_ to go straight ahead - the thing that later on was changed to the white-on-blue arrow. (examples: https://de.wikipedia.org/wiki/Bildtafel_der_Verkehrszeichen_... but the sign must be older than that).

If you want to be picky, the "you must" signs generally had a narrower red ring than the "you must not" ones, but even that rule is not always adhered to on the linked page.

I think the slash was added in some cases because there's an old German sign with a black arrow on a white background with a red ring, that means _you must go this way_ instead of _you must not go this way_ as we'd read it today. So the slash on all such signs (no left turn etc.) is to make it doubly clear this is a prohibition not an instruction.

Fun fact: the German Empire had an additional convention that if the symbol (e.g. a motor car) was shown in outline instead of filled in, then the prohibition only applied on Sundays.

EDIT: looking at https://commons.m.wikimedia.org/wiki/Category:Diagrams_of_hi..., the 1927 German sign for "parking _allowed_" was a black P on a white background with a red circle; the prohibition sign contained the text "Parken verboten" (parking forbidden). So I can see why the German delegate might have objected to making the new "no parking" sign their old "yes you can park here" sign!

In the corporate world, the most meaningful implementation that has no ambiguity seems to be this one:

https://images.fineartamerica.com/images/artworkimages/mediu...

The article traces the symbol to March 1931's League of Nations "Convention Concerning the Unification of Road Signs" in Geneva, Switzerland.

But someone must have suggested it so it could be added to the convention. Who was that?

According to https://history.stackexchange.com/questions/74386/what-is-th... it was developed by a subcommittee of the convention, apparently from scratch (or at least, from signs that didn't have a slash).

My guess is Pflug, the German delagate, to avoid the new international "no parking" sign being identical to the old German "parking allowed" sign.

A very American article. To Europeans (and people in most other places) the answer is obvious that it comes from the street signs. The only open question is where their designers got the idea from.

I was rather bemused that the article takes a third of its length before getting to that point, and almost glances over the remaining question (apparently it comes from the subcommittee that designed the no parking and no stopping signs).

Being Australian, I accidentally rode my bicycle down the entry lane to a German autobahn after seeing a sign with a bike and a circle around it (not through it).

I did the same thing in the Netherlands. And promptly studied the local road signs after that terrifying experience.

You get far by only knowing the main categories: circle with red border is forbidden, blue circle is mandatory, blue square is informational.

White (yellow in some countries) signs with a red circle are always prohibition signs (or speed/weight limits), no matter if there is a bar or not - actually only the "no stopping" and "no parking" signs have bars (two for no stopping). If something is allowed, the sign is white on blue.

Except in Ireland, where the people deciding on the signs really didn't read the standard.

See "Taxi stand" and "Parking": https://en.wikipedia.org/wiki/Comparison_of_European_road_si...

Oh wow, that's terribly confusing.

Actually that parking sign may come from an old German parking sign, see this comment: https://news.ycombinator.com/item?id=39666622 .

Just to nitpick further, white on blue does not mean "allowed". It means "mandated".

To nitpick just a bit further, white on blue means obligatory if it's a circle but just information if it's a rectangle.

...except if it's the "one way street" sign used in some countries (https://en.wikipedia.org/wiki/One-way_traffic), which is definitely mandatory.

Well, not really. This sign is an indication that you will not encounter oncoming traffic.

The other end of the road will see a "No Entry" sign (red disc with a white horizontal bar) and any side street will get a "mandatory direction" sign (a blue disc with a with circle and a white arrow) that shows which direction is mandatory or a "no turning" sign showing which direction is prohibited. The square blue sign with an arrow is an indication that someone else has mandatory or prohibition signs.

For example here: https://maps.app.goo.gl/PwAYqUffz6uPLVZW6 you can see a "no right turn", a "one-way traffic" sign, and a "no entry" sign (all saying "except bikes"). The "one-way traffic" is definitely informative, it would be a disc otherwise.

Now, I'm used to France, Belgium and the UK but looking at this chart: https://en.wikipedia.org/wiki/Comparison_of_European_road_si...

it seems like it's less universal than I thought. Using just a rectangle with an arrow when coming from a side street rather than a circle makes no sense to me unless there are also no entry/no right turn/mandatory left turn signs as well.

That's an interesting example, as white arrow/arrows on blue in circle also exists, which limits (or otherwise indicates) the directions you can continue.

The one-way traffic sign does fit in, but most commonly you see it in situations where it's actually just informational, like the entrance of a road. In this case it doesn't limit you in any way, it's not like you have to enter that road. You will see a no entry sign on the other side of the intersection anyway, which does limit you. But it does inform you that you shouldn't expect oncoming traffic.

The horizontal one-way road sign is less common, and is often used in T-junctions. There it arguably does double duty.

It does mean that after entering that road you aren't allowed to turn around and go back, so there is a bit of a mandatory aspect there. Nevertheless I think it still fits best with the informational signs, also to separate it from the white arrow on a blue circle.

As an American kid, I didn't understand some of the signs in this Lego set: https://www.bricklink.com/v2/catalog/catalogitem.page?S=6315... - and they had already modified it somewhat to make it more clear.

The "two cars next to each other" was always a perpetual mystery as to where I should put it.

I was very surprised to learn just how new this symbol is. I'm a bit too young for it but apparently there were times in my parents' lifetimes when few Americans would have understood it.

It's not new. It's been an European standard traffic sign since the 1930s.

That's pretty new!

Pretty much everything except farming and church is new.

Farming has been around for over five times longer than the church.

Uhh...I don't have sources but I'd imagine humans prayed to _something_ before they went mammoth hunting or picking berries long before farming.

Organized religion, writing, and agriculture were a self-supporting set. The people today that didn't develop that set don't pray.

Agriculture == 4chan/internet

Religon == memes

Writing == telling memes to others

The Church requires that you've decided this needs to be organized, all you need to start praying before you go hunt for food is superstition.

The Princes Alice experiments show why superstition might be valuable (and so get preserved in a culture) if you don't have much technology to provide oversight. Children were told to perform a task and that an (invisible) Princess, Alice is watching to check they don't cheat while the adults are away. Superstitious children didn't cheat because they believed in Alice watching them. The non-superstitious children cheated, after first verifying that in fact Alice does not seem to exist (e.g. passing their hand through space supposedly occupied by the invisible princess)

"The church" is a metonym for Christianity.

In this case I think it refers to organized religion in general, which is older, roughly dating to the beginning of agriculture and city formation.

That interpretation only works if you desperately want the comment containing the phrase "the church" to be wrong. If you insist on this unusual interpretation, then yes, farming isn't at least five times older than the church. But if you go with the usual interpretation of "the church" as a metonym for Christianity, as was very clearly intended by the implications of the statement, it is correct.

Why not go talk to some Muslims about the Islamic church? Or some Hindus about the church of Shiva? I'm sure you'll find the discussion edifying!

Oops, yeah, you are correct about the relative ages, I wrote a bit too fast there.

There was an HN discussion in 2020 about the oldest business or commercial establishment in various countries and/or continents. Many of those are involved with, variously, food service, alcohol, teaching, construction, or banking. In part because those are activities which have been with humans (or at least civilised, that is, inhabiting-cities humans) since the beginning, and have not been supplanted by some newer activity.

<https://businessfinancing.co.uk/the-oldest-company-in-almost...>

HN discussion: <https://news.ycombinator.com/item?id=22426289>

You do know what "the oldest profession in the world" refers to, though?

The symbol has existed for some good 2/3 of the time international standards existed as a concept.

As the articles says on the end, we don't know how old non-standardized versions of it are.

If you think about it, though, the symbol has been around longer than most people today have been alive, and for a substantial amount of the time people have been driving. Compared to other symbols, it may be fairly "new" (for example, the Christian cross or Islamic crescent), but in the realm of widely standardized symbols, it's pretty old.

That doesn't necessarily contradict what GP said...

> an European standard traffic sign since the 1930s

and how's the standardization drive going? https://en.wikipedia.org/wiki/Prohibitory_traffic_sign#No_mo... (link somebody else posted)

Fine? They are all essentially the same, with different artistic style.

There can be regional differences on what signs are required. I only checked the Italian one, but that sign only prohibits cars, motorcycles are still allowed. If both are prohibited, they presumably display both signs, or prohibit all vehicles (including bicycles) with that sign.

>Fine? They are all essentially the same, with different artistic style.

many don't have the slash; some do

Pretty well, so to see.

A similarly recent symbol, from the late 1950s, is the peace sign. Designed by Gerald Holtom: https://en.wikipedia.org/wiki/Gerald_Holtom (wiki page for Mr Holtom includes a discussion of the peace symbol story)

And then there is this no entry symbol, which makes no sense:

https://imgur.com/a/oSV1Aen

Reading the symbol it looks like a person prohibiting entry, crossed out. A double negative.

Re. ubiquity making things hard to find— Recent application naming is infuriating! Consider, in GNOME, for example, Nautilus vs Files. "GNOME Files" does not, of course, help. Same with "Apple Photos".

GRRR!

About as helpful as trying to debug "An error has occurred".

Trying to hide the real name of the application is some weird gnome pastime.

Apple Photos, Music, Numbers, Notes… It’s truly exasperating trying to surface an answer for a question like “how do I sort photos in Apple Photos by date of photo not date added?”

At least Google figured out after the fact that golang made more sense than go.

renaming iTunes to "music" has pissed me off

and making "Apple Music" also refer to a subscription service is even worse.

you can only get away with so much by using "music.app" and "photos.app" - and it really doesn't apply on the phone. (Aside: how long until the iPhone is just the Apple Phone?)

AKA "bend dexter", in the sense of heraldry. https://en.wikipedia.org/wiki/Bend_(heraldry)

(Credit for this observation goes to Ryvar in the Metafilter discussion of this article.)

Interesting!

I'd heard it referred to as a "bar sinister" before but when I looked it up I couldn't find anything to confirm that. I hadn't thought of looking it up in the context of heraldry.

I suppose dexter when it's left-to-right and sinister when it's right-to-left?

Yeah, which maybe makes it punnily appropriate that Ghostbusters has always used the "bend sinister" version given the theme of ghosts and the modern connotation of "sinister".

I struggle to find this emoji on Slack on a regular basis.

Just type “no” in search and it should be one of the top options.

Most Americans probably became aware of this when it was used in 1984’s Ghostbuster's

TL;DR:

> March 1931, when the League of Nations, attempting to manage the sudden explosion in road traffic, convened a Convention Concerning the Unification of Road Signs in Geneva

It comes from traffic signs in the first half of the 20th century.

Sorry to be that guy, but I was less fascinated and more bemused by this one. Surely the origins of this would simply be somebody formalising the representation of “crossing something out”? An act as old as cave paintings, one assumes.

Why assume instead of reading the article?

Can you find examples older than 100 years old that show a thing crossed out to mean "don't do this thing?" And how close are they to this representation? That's what the author was trying to find out.

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