Template talk:Mw lang

When is mw_lang different from iso 639 name?

This is probably just a documentation issue, but I am unclear how this template, which "uses MediaWiki's language set" (per the sentence at the top) differs from {{iso 639 name}}. At first, I thought it was related to languages for which we have a Wikipedia in that language (which I believe is predicted by Special:SiteMatrix, although I am not 100% certain of that). This is just a small sampling where I tried to get some representative examples, e.g., one where ISO and SiteMatrix codes are different; one exists but locked; a couple non-existent, but it's hard to generalize from these few examples.

Lombard language – existing Wikipedia lmo: ISO-639=lmo; SiteMatrix code=lmo:

Lombard Wikipedia exists (at lmo:) and all the template values match up:

• {{iso 639 name|fn=iso_639_name_to_code|Lombard}} → lmo; {{mw lang|fn=code_from_name|Lombard}} → lmo
• {{#language:lmo|en}} → Lombard
• {{iso 639 name|fn=iso_639_code_exists|lmo}} → true; {{mw lang|fn=is_code|lmo|en}} → true
• {{iso 639 name|fn=iso_639_name_exists|Lombard}} → true; {{mw lang|fn=is_name|Lombard|en}} → true
• {{iso 639 name|fn=iso_639_code_to_name|lmo}} → Lombard; {{mw lang|fn=name_from_code|lmo|en}} → Lombard

Rohingya language – nonexistent at rhg:/incubating; ISO-639=rhg; SiteMatrix code=rhg:

We don't have a Rohignya Wikipedia, but all the template values match up, and it is being incubated at https://incubator.wikimedia.org/wiki/Wp/rhg/Main_Page.

• {{iso 639 name|fn=iso_639_name_to_code|Rohingya}} → rhg; {{mw lang|fn=code_from_name|Rohingya}} → rhg
• {{#language:rhg|en}} → Rohingya
• {{iso 639 name|fn=iso_639_code_exists|rhg}} → true; {{mw lang|fn=is_code|rhg|en}} → true
• {{iso 639 name|fn=iso_639_name_exists|Rohingya}} → true; {{mw lang|fn=is_name|Rohingya|en}} → true
• {{iso 639 name|fn=iso_639_code_to_name|rhg}} → Rohingya; {{mw lang|fn=name_from_code|rhg|en}} → Rohingya

Bhojpuri language – existing Wikipedia bh: ISO-639=bho; SiteMatrix=bh (contrast bh='Bihari' in ISO-639)

{{hatnote|This template uses bh the other one uses bho; over there, bh is Bihari language (but see the footnote in the Infobox).

• {{iso 639 name|fn=iso_639_name_to_code|Bhojpuri}} → bho; {{mw lang|fn=code_from_name|Bhojpuri}} → bh
• {{#language:bho|en}} → Bhojpuri
• {{iso 639 name|fn=iso_639_code_exists|bho}} → true; {{mw lang|fn=is_code|bho|en}} → true
• {{iso 639 name|fn=iso_639_name_exists|Bhojpuri}} → true; {{mw lang|fn=is_name|Bhojpuri|en}} → true
• {{iso 639 name|fn=iso_639_code_to_name|bho}} → Bhojpuri; {{mw lang|fn=name_from_code|bho|en}} → Bhojpuri
• {{iso 639 name|fn=iso_639_code_to_name|bh}} → ; {{mw lang|fn=name_from_code|bh|en}} → Bhojpuri

Kalaallisut language (Greenlandic) – locked Wikipedia kl: ISO-639=kal/kl; SiteMatrix=kl

ISO 639-1 works in both; 639-2 only in the other template; https://kl.wikipedia.org exists but is locked.

• {{iso 639 name|fn=iso_639_name_to_code|Kalaallisut}} → kl; {{mw lang|fn=code_from_name|Kalaallisut}} → kl
• {{#language:kl|en}} → Kalaallisut
• {{iso 639 name|fn=iso_639_code_exists|kl}} → true; {{mw lang|fn=is_code|kl|en}} → true
• {{iso 639 name|fn=iso_639_name_exists|Kalaallisut}} → true; {{mw lang|fn=is_name|Kalaallisut|en}} → true
• {{iso 639 name|fn=iso_639_code_to_name|kl}} → Kalaallisut; {{mw lang|fn=name_from_code|kl|en}} → Kalaallisut
• {{iso 639 name|fn=iso_639_code_to_name|kal}} → Kalaallisut; {{mw lang|fn=name_from_code|kal|en}} →

Klingon language – nonexistent Wikipedia tlh: constructed language Klingon; SiteMatrix (absent)

Absent from Special:SiteMatrix, but conversions work in both, anyway (including in {{mw_lang}}):

• {{iso 639 name|fn=iso_639_name_to_code|Klingon}} → tlh; {{mw lang|fn=code_from_name|Klingon}} → tlh
• {{#language:tlh|en}} → Klingon
• {{iso 639 name|fn=iso_639_code_exists|tlh}} → true; {{mw lang|fn=is_code|tlh|en}} → true
• {{iso 639 name|fn=iso_639_name_exists|Klingon}} → true; {{mw lang|fn=is_name|Klingon|en}} → true
• {{iso 639 name|fn=iso_639_code_to_name|tlh}} → Klingon; {{mw lang|fn=name_from_code|tlh|en}} → Klingon

Can you beef up the doc to explain what exactly mw_lang is doing, what to expect under differing circumstances, and when this template is appropriate as opposed to {{iso 639 name}}? Two brief subsections ===When to use=== and ===When not to use=== under section § Usage, along with a longer intro sentence at the top would be ideal. There may be some tricky edge cases (as there often are in language) which may work better as explanatory notes and resolved in a ==Notes== section. Thanks, Mathglot (talk) 00:24, 22 June 2026 (UTC)