In terms of navigation from article-items to Commons categories, the policy is very straightforward: set and use the P373 property.

This property also makes the inverse very straightforward, to go from a Commons category to a Wikidata item:  use the script
    https://commons.wikimedia.org/wiki/User:TheDJ/wdcat.js
or the tweaked version at
    https://commons.wikimedia.org/wiki/User:Jheald/wdcat.js
which handles diacritics properly.  These scripts automatically add a Reasonator link to the Commons category whenever there is a Wikidata article-like item pointing to it with a P373.


What we have at the moment is the worst of all worlds -- namely inconsistency which is getting worse.

As a result people don't know what to do, and they are not setting the P373 property -- with the result that scripts and queries don't find the connections that they should.

What we need is clarity and systematic consistency.  Then it is an easy step to adjust the user-presentation to do the right thing.


  -- James.

On 27/08/2015 14:03, Romaine Wiki wrote:

No we have not a clear policy on only linking sitelinks to categories if
the item itself is about a category. So not let's not break that.

You suggest to break down almost the complete navigational structure
Commons has in relationship with Wikipedia, and makes it possible to find
articles that are about the same subject as the category. Without it
becomes almost impossible to identify a category on Commons to be related
to an article in Wikipedia.
Sorry, but your proposal is insane and making the navigational situation a
thousand times worse. And does it make anything better? No, totally not.
Only the opposite: worse.

Wikidata is currently heavily used to connect categories on Commons to
articles on Wikipedia. This so that interwikilinks are shown on the
category on Commons to the related Wikipedia article. This for navigational
purposes but also to uniquely identify categories on Commons to articles on
Wikipedia and items on Wikidata.

How nice Commons galleries are giving an overview, they are crap in
speaking of navigational purposes. For every subject a category on Commons
is created and used and the Commons categories form the backbone to media
categories.

It has been pointed out for a long time that the linking situation on
Commons is problematic and this is a software issue, not a user side issue.
This consists out of:
* There can only be added one sitelink to an item.
* If no sitelink added (but only added as property), a Commons category
can't show the interwikilinks.
* If a category and an article on Wikipedia/etc exist for a subject, only
one of them can be shown on the Commons category.

The annoying part is that some large wikis, especially the English
Wikipedia, creates too many categories that are not created on other
Wikipedias. This causes that categories on Commons are only linked to a
category on Wikipedia, which is useless for most other wikis and on Commons
we miss an interwikilink to the related article.

A gallery on Commons is a great way as alternative to show images, but is
not suitable for navigational purposes, as that requires a much higher
coverage and being a backbone everything relies on. On Commons only
categories have that function. A counter proposal makes more sense: no
Commons galleries as sitelinks any more and having Commons galleries only
as property added.

But this only solves a part of the problem: on Commons I would like to see
somehow that both the related category as the related article are shown.
Example: on the Commons category for a specific country both the country
category on Wikipedia is linked as the article on Wikipedia is linked.

Something I have been wondering about for a long time is why there are 2
places on an item where a Commonscat is added. I understand the development
and technical behind it, but this should not be needed.

So the developers of Wikidata should try to find a way to show both groups
of interwikilinks on categories on Commons.

As long as this is not resolved in software, this problem of 2 items both
strongly related to a Commons category keeps an issue.

Romaine





2015-08-27 11:29 GMT+02:00 James Heald <j.heald@ucl.ac.uk>:

A few days ago I made the following post to Project Chat, looking at how
people are linking from Wikidata items to Commons categories and galleries
compared to a year ago, that some people on the list may have seen, which
has now been archived:


https://www.wikidata.org/wiki/Wikidata:Project_chat/Archive/2015/08#Trends_in_links_from_items_to_Commons


A couple of headlines:

* Category <-> commonscat identifications :

** There was a net increase of 61,784 Commons categories that can now be
identified with category-like items, to 323,825 Commons categories in all

**  96.4% of category <-> commonscat identifications (312,266 items) now
have sitelinks.  This represents a rise in sitelinks (60,463 items)
amounting to 97.8% of the increase in identifications

**  80.0% of category <-> commonscat identifications (259,164 items) now
have P373 statements.  This represents a rise in P373 statements (8,774
items) amounting to 14.2% of the increase in identifications


*  Article <-> commonscat identifications :

** There was a net increase of 176,382 Commons categories that can now be
identified with article-like items, to 884,439 Commons categories in all

** 23.4% of article <-> commonscat identifications (207,494 items) now
have (deprecated) sitelinks. This represents a rise in sitelinks (112,595
items) amounting to 63.8% of the increase in identifications.

** 91.3% of article <-> commonscat identifications (807,776 items) now
have P373 statements. This represents a rise in P373 statements (110,727
items) amounting to 62.8% of the increase in identifications


*  In addition, a recent RfC showed considerable confusion as to what
actually was the current operational Wikidata policy on sitelinks to
Commons:


https://www.wikidata.org/wiki/Wikidata:Requests_for_comment/Category_commons_P373_and_%22Other_sites%22


In view of the trends above; and the need for predictability and
consistency for queries and templates and scripts to depend on; and
particularly in view of the apparent confusion as to what the operational
policy currently actually is, can I suggest that the time has come for a
bot to monitor all new sitelinks to Commons categories,
*  adding a corresponding P373 statement if there is not one already, and
*  removing the sitelink if it is from an article-like item to a
commonscat.


I believe we have clear policy on only sitelinking commons categories to
category-like items, and commons galleries to article-like items; but there
is currently confusion and unpredictability being caused because these
relationships are not being enforced -- breaking scripts and queries.

It's time to fix this.


All best,

   James.


_______________________________________________
Wikidata mailing list
Wikidata@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikidata

_______________________________________________
Wikidata mailing list
Wikidata@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikidata

_______________________________________________
Wikidata mailing list
Wikidata@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikidata