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I just tried to add a tag for "implementation-defined-behavior" on SO but I couldn't because of the 25 char limit. I had to resort to an abbreviation (), which is rather ugly and to some extent thwarts the purpose of tags, i.e. easy indexing.

Although I acknowledge that too long tag names could be unwieldy, sometimes there are technical terms that cannot be abbreviated in any useful way (especially when there is no widespread acronym).

Could an increase of that limit be considered?

share|improve this question
To downvoters: would you like to elaborate why my proposal is not welcome? – Lorenzo Donati Sep 22 '13 at 21:48
I'm sure that tag will be removed quickly, if not already. – animuson Sep 22 '13 at 21:50
@animuson is it for its length? I find it strange that we can have "unspecified-behaviour", "undefined-behavior" but not that one. – Lorenzo Donati Sep 22 '13 at 21:52
@LorenzoDonati - It's a meta tag. – nickb Sep 22 '13 at 21:54
@nickb Thanks for the pointer. I'm not totally convinced, yet. Although in general "unspecifed-behavior" could be seen as a meta-tag, in C and C++ "unspecified-behavior" (e.g.) is a strictly defined technical term, which pops-up continuously in threads: it is about the content of the posts. – Lorenzo Donati Sep 22 '13 at 21:59
@nickb: It’s not a meta-tag. “homework” is about the circumstances under which the question was asked. “implementation-defined-behavior” is about the question. – Ryan O'Hara Sep 22 '13 at 22:00
up vote -2 down vote accepted

If you're wanting to exceed the maximum character limit for a new tag, experience has taught us that you probably want to re-think the tag and see if it can be broken out into more than one. Animuson suggested some good alternatives that could be used interchangeably and applied to a broader range.

Remember also that tags are candidates for inclusion in the title of the page when viewed, so the constraints are as practical as they are philosophical. Raising the limit here would be a little self-defeating in both aspects.

Others have noted that what you were trying to create is a meta tag and I don't think this is the case. The term oddly specific comes to mind, but that just points to the fact that the tag would be more useful if split into several.

And please, whatever you do, don't invent a programming language with a name that exceeds 25 characters or I'll have to eat this with salt & pepper.

share|improve this answer
Thank you Tim. I think yours is the best answer to my doubts. I recognize, now that I understand the bigger picture, that asking for a higher limit was not really appropriate. I still think that the specific case is an oddball: oddly specific really captures the essence of the problem, so thank you for recognizing that. – Lorenzo Donati Sep 23 '13 at 18:27
BTW, many other people have provided useful insights (thanks, anyway!), but their answers weren't fully satisfactory, since they failed to recognize the fact that "implementation-defined" (or sth else) doesn't really hit the spot IMO (even if some come close). I wish there could be a way to ask the C/C++ SO community about that, since this issue is really specific to them. I fear that people not having enough experience in these languages maybe don't get the same "gut feeling" for what could be deemed just nitpicking. – Lorenzo Donati Sep 23 '13 at 18:31
As an aside, if I ever happened to invent a new language, I'd rather choose a two-letters name (cool one letters are almost all taken :-). Although "dragon" could be a cooler name, and much shorter than 25 letters! ;-) – Lorenzo Donati Sep 23 '13 at 18:34
“Don't invent a programming language with a name that exceeds 25 characters” — that's fine for SO, but how about caring about the rest of the network sometimes? I've hit this limit with diverse things like the name of software packages on Unix & Linux, the name of calculi on Computer Science, and the title of works on Science Fiction & Fantasy, all of which are the local equivalents of programming languages in terms of taxonomy and thus tag names. Therefore, please eat this status-declined with soy sauce, pickles and Spice. – Gilles Jun 6 '15 at 19:17
Hell, not just calculi but whole domains. We have a natural-lang-processing tag on CS.SE, which is silly because nobody would search for “natural lang processing”: it's either “natural language processing” or “NLP”. On this specific example, maybe we should use nlp as the tag name… that's good for the people who know what it is, but then we get complaints from people who don't know the abbreviation. – Gilles Jun 6 '15 at 19:23
Can we haz natural-language-processing, windows-deployment-services and my-little-pony-friendship-is-magic? In less than 25 weeks? – Gilles Jun 12 '15 at 20:13
And there are games with long names, that's a long-standing, well-motivated request. And Portuguese needs more letters than English. – Gilles Jul 20 '15 at 12:55

I can see the value of longer tag names in some contexts as noted by Giles. So there are a number of courses of action possible:

  1. No change: simple, but does not really fix .
  2. Increase to 27 chars: fixes one specific problem, but both makes it more difficult for SO and does not help SFF if someone were to want to tag questions about John Joseph Adams book (44).
  3. Change this on a per site basis: This has the advantage of tuning it to the subject at hand so SO would be 25, CS at 30, and SFF at 50 (numbers subject to improvement by picking a source other than thin air). But this does not help with the the fact that in most cases long tag names can be improved and shortened.
  4. Make long tag names require high rep or a moderator to create or approve: those with create tag privilege can create tags up to 25 chars long, Anything else would be discussed on the site meta and placed by a high rep user or a placement attempt would go into a approval queue. This can be a new privilege or just lumped in with moderator tools.
  5. My favorite, combine options 3 and 4 so that the length limit on tags is site specific and can be bypassed by moderators and high rep users as needed on a case by case basis.
share|improve this answer

There is always a better way to tag something than using an atrociously long tag name and without using silly abbreviations which are even worse and extremely hard to find in the tag suggestions.

For your specific case, I would just drop one of the words. Possibilities:

Just make sure it gets a tag wiki and excerpt that clearly defines the tag's purpose.

If you're ever unsure about how a tag should be created due to the character limit, come to Meta and ask the community to help you. But increasing the character limit just isn't a good option.

share|improve this answer
I'd argue that the “implementation” is rather the important part — the standard defines lots of behavior that you can rely on from implementation to implementation, but it also leaves certain areas for implementations to define their own semantics, possibly making code non-portable between implementations. defined-behavior doesn't say whether the standard or implementations define it. You could say which in the tag wiki, but then you'd have to look at it to tell; it's not obvious at a glance like most other tags are. – icktoofay Sep 22 '13 at 22:31
I appreciate the advice, but I disagree on its applicability in this specific case. Just tagging as "defined-behaviour" could make more harm than good. There are atrocious discussions in C/C++ threads where something simply described as "defined behaviour" is the subject of heated debate. These technical terms (unspecified- impl.defined- and undefined-behavior) are of utmost importance in C/C++: failing to understand the implications may lead to erroneous programs with dire consequences (that's the C heritage). I don't think that an approximately named tag would satisify the C/C++ community. – Lorenzo Donati Sep 22 '13 at 22:43
@icktoofay If that part is important, then there's always implementation-behavior… or you could even drop the word "behavior" and make implementation-defined... – animuson Sep 22 '13 at 22:44
I think implementation-defined is probably the best abbreviation of this one. – Ryan O'Hara Sep 22 '13 at 22:50
“defined-behavior” and “implementation-defined” have absolutely nothing to do with the intended meaning of the tag, they would be even worse than the abbreviated “implem.-defined-behavior”. The solution to “the name doesn't fit” isn't “pick an unrelated name that fits”. – Gilles Sep 23 '13 at 9:12

In my opinion and in general, tags must be as shorter as possible, for readability, usage...

And create exceptions to the rules can lead to abuse...

Concerning your specific case, I don't know what would be the best but I really think @animuson suggests you valuable possibilities.

So for ?


share|improve this answer
I'd agree, but some folks at the C standard committee made a different choice, so we have to live with such mouthfuls as "undefined-behavior" and "implementation-defined-behavior". We cannot call them in another way, although "dragons" and "unicorns" would be shorter :-) – Lorenzo Donati Sep 22 '13 at 22:05
It'd take a while to burninate this entire thing. :-) – Jamal Sep 22 '13 at 22:55

The tag you want to create is Meta Tag. Tags should be used for technologies or libraries involved in questions. Such 'canonical' tags don't tend to be so extremally long, so the limit is actually doing what it is supposed to do.

Tags should be used for tags and not for descriptions. This is what Jeff's post is about.

share|improve this answer
In what way is it a meta tag? – doppelgreener Sep 23 '13 at 8:11
@JonathanHobbs it is about the symptoms or the implementation, not about the domain of the problem. What means 'implementation based'? Is it C, PHP, Java? But it's my interpretation of Jeff's post and the contept of meta-tags. Anyway, if you need to create such a long tag, something is wrong with it. – Danubian Sailor Sep 23 '13 at 8:16
I agree that something's wrong, but not that it's a meta tag. If you're asking about implementation-defined behaviour in C#, it's a perfectly suitable tag describing the content of the question, isn't it? – doppelgreener Sep 23 '13 at 8:26
I say that being fully open to the possibility it isn't - I have yet to wrap my head around what is and isn't a meta tag. – doppelgreener Sep 23 '13 at 8:40

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