In general, this would have issues with spaces being encoded as _ instead of %20 or + as required, and that it would all fall down if short urls weren't in use (but if we're just looking at Wikinews specificly, that might not be that big a deal).

"Tags" are quite widely used in the blog world, and I believe there are many real world use cases of people using such information, so it probably would be cool. I personally think that most (all) wikis category structures are essentially close enough to "tag"'s that this could apply everywhere, but I suppose that's debatable.

Relevant info: http://microformats.org/wiki/rel-tag

HTML5 spec also mentions it very briefly: "The tag keyword indicates that the tag that the referenced document represents applies to the current document."

andy wrote:

The encoding of spaces should not be an issue. To a well-written parser, the tags "Turkey Vulture" "Turkey_Vulture" and "Turkey%20Vulture" should be synonymous.

(In reply to comment #2)

The encoding of spaces should not be an issue. To a well-written parser, the
tags "Turkey Vulture" "Turkey_Vulture" and "Turkey%20Vulture" should be
synonymous.

Standard seems to imply that Turkey_Vulture and Turkey%20Vulture are two different tags (with potentially) different meanings. Well it might make sense to assume underscore and space are synonyms, I don't feel we should assume that unless the standard says so.

andy wrote:

If by "spec" you mean http://microformats.org/wiki/rel-tag it says "Spaces can be encoded either as + or %20." (so "Turkey+Vulture" is also a synonym) but is silent on underscores. Note, though, that it's a draft, and is intended to reflect real-world usage. Someone who can be bothered to deal with the "not invented here" attitude of the microformat community might like to raise this as a proposed change to the draft.

None the less, it's still worth adding the proposed change to MediaWiki. "Turkey_Vulture" (the format we emit) is a useful and valid tag in its own right.

andy wrote:

P.S.

Note also the use of underscores in several of the examples on:

http://microformats.org/wiki/rel-tag-spaces

including Wikipedia.

(In reply to comment #5)

P.S.

Note also the use of underscores in several of the examples on:

http://microformats.org/wiki/rel-tag-spaces

including Wikipedia.

Well in that case I withdraw my previous objection on those grounds.

it might be a good idea to add an option/extension (probably not a default setting, though)

I don't think this should be an option.

I read again the specification, the examples, the list of current use, and all three explicitly mention categories as acceptable objects for rel="tag".

To add an option has a cost in documentation, maintainability and support.

In the other hand, to add a class in markup doesn't have any obvious drawback.

Would someone see any objection to unconditionally add rel="tag" to category links?

@TheDJ any opinion on this task?

Change 326373 abandoned by Thiemo Kreuz (WMDE):
[mediawiki/core@master] Add rel="tag" to categories

Reason:
Unfinished draft with no code. Let's free up our backlogs a bit.

https://gerrit.wikimedia.org/r/326373