Probably a duplicate of the very old T20562: Indicate in output whether an interwiki link is marked local, for which I submitted a patch more than three years ago (shock horror, it needs rebasing!)

Edit: Maybe not a dupe, this is broader. But still related.

This request is a bit too much Wikimedia-centric. The idea of the interwiki map is to hold together all the MediaWiki wikis in an collaborative division of labour (http://meatballwiki.org/wiki/InterWiki ). Wikimedia wikis might decide that they no longer care about integrating with non-Wikimedia wikis, but for most wikis the fact that an interwiki is not local makes very little difference. It's also a two-way street: do we prefer non-Wikimedia wikis to refer to Wikipedia articles, Wiktionary lemmas etc. as if they were local, or do we want to encourage forking?

That said, it's true that many Wikimedia projects (especially Wikipedias) treat the interwiki links as external links from a policy perspective in many cases, so I can understand the wish to convey this distinction visually. For that, I agree T20562 is a reasonable solution, preferably controlled by a configuration setting.

Does this report also ask for non-visual changes?

In T191405#4104637, @Nemo_bis wrote:

Does this report also ask for non-visual changes?

No, I personally think we should be doing this regardless of any visual changes. However if we add external class, the links will start using the external link symbol by default. So I do think we need to determine the visual effects before rolling out such a change.

In T191405#4104675, @TheDJ wrote:

However if we add external class, the links will start using the external link symbol by default.

I think that is a good thing. That is why I put the patch forward in the first place.

Interwiki links to non-local sites are, from the user's perspective, external links, so they should get the external link icon. Say what you like about wikis seamlessly linking to each other, but I think that battle was lost years ago with the decline of "wiki culture" (as propounded on Meatball) and insular nature of most MW sites nowadays.

The interwiki database already has the notion of "local" links, which for example, triggers whether or not it can be a language link, whether it can be redirected to, and whether to display an interstitial page if entered in the search field (example).

The same could be applied to link rendering, to render interwiki links as regular external links if their destination is not farm-local.

Parsoid/VisualEditor actually render all interwiki links as external links (including local ones), but that's a separate bug, as links should render the same way between "read" and "edit" modes. (T185083)

In T191405#4104637, @Nemo_bis wrote:

This request is a bit too much Wikimedia-centric. The idea of the interwiki map is to hold together all the MediaWiki wikis in an collaborative division of labour (http://meatballwiki.org/wiki/InterWiki ).

Maybe that was the original idea in the late 1990s or early 2000s, but it has clearly been abandoned long ago. The current "interwiki" map has contained many non-wikis for many years now, e.g. Google, ArXiV, IMDb, Bugzilla, JSTOR and VIAF. I appreciate the awareness of early wiki history and nostalgia for bygone decades, but it shouldn't hold us back from making improvements to Wikimedia sites in 2018.

Does this report also ask for non-visual changes?

An important non-visual difference between interwiki links and external links is that the latter are tagged with rel="nofollow".

In T191405#4464038, @Tbayer wrote:

In T191405#4104637, @Nemo_bis wrote:

Does this report also ask for non-visual changes?

An important non-visual difference between interwiki links and external links is that the latter are tagged with rel="nofollow".

It should be noted that the current proposed patch: https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/146711/2/includes/linker/LinkRenderer.php
does not have this effect. These would still be interwiki links (with interwiki policies). They just would get an additional class, which they would share with external links.

This totally stalled, but i still think its a good idea...
It is my intent to merge https://gerrit.wikimedia.org/r/146711
within the next month or so.

Change 146711 had a related patch set uploaded (by Krinkle; owner: TTO):
[mediawiki/core@master] Add "external" class to non-local interwiki links

https://gerrit.wikimedia.org/r/146711