Nothing to do AFAIS. It works for wikidata already, see https://test.wikidata.org/wiki/Q149653 last monoligual statement.

For labels, descriptions and aliases a language needs to be added to ULS and needs Langcom approval. I believe it needs to be requested on meta. But @GerardM @jhsoby can tell more about these rules.

In T196473#4258202, @Raymond wrote:

Nothing to do AFAIS. It works for wikidata already, see https://test.wikidata.org/wiki/Q149653 last monoligual statement.

The request isn't related to monolingual text. Labels, Descriptions and Aliases aren't using the languages for monolingual texts.

In T196473#4258213, @Mbch331 wrote:

The request isn't related to monolingual text. Labels, Descriptions and Aliases aren't using the languages for monolingual texts.

Right. My above answer was a bit short. shy was added to Names.php per T194047. And therefore shy can be used for Labels, Descriptions and Aliases already: https://test.wikidata.org/w/index.php?title=Q149653&type=revision&diff=391466&oldid=384181

In T196473#4258228, @Raymond wrote:

In T196473#4258213, @Mbch331 wrote:

The request isn't related to monolingual text. Labels, Descriptions and Aliases aren't using the languages for monolingual texts.

Right. My above answer was a bit short. shy was added to Names.php per T194047. And therefore shy can be used for Labels, Descriptions and Aliases already: https://test.wikidata.org/w/index.php?title=Q149653&type=revision&diff=391466&oldid=384181

Just tested it on production and it gives an API error:

{"error":{"code":"not-recognized-language","info":"The supplied language code was not recognized.","messages":[{"name":"wikibase-api-not-recognized-language","parameters":[],"html":{"*":"The supplied language code was not recognized."}}],"*":"See https://www.wikidata.org/w/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce> for notice of API deprecations and breaking changes."},"servedby":"mw1316"}

This is odd, since the language was added in 1.32.0-wmf.5 and Wikidata is running on 1.32.0-wmf.6

I found where I went wrong (and probably @Vikoula5 as well): shy isn't accepted, but shy-latn is.

@Mbch331 for the moment we use only shy-lat, you are right. can you do it for shy-lat ?

In T196473#4259376, @Vikoula5 wrote:

@Mbch331 for the moment we use only shy-lat, you are right. can you do it for shy-lat ?

The official language code for shy in latin script is shy-latn, so you need to use that one.

@Mbch331
Yes, but the shy-Latn doesn't exist in wikidata too. How can a used it ?

In T196473#4261717, @Vikoula5 wrote:

@Mbch331
Yes, but the shy-Latn doesn't exist in wikidata too. How can a used it ?

It exists: https://www.wikidata.org/w/index.php?title=Q4115189&diff=690888218&oldid=690786189, so where are you missing it?

Ok, I find it, but there is a problem here withe the ''Lua error in Module:Languages at line 8: Error2''..
Maybe there are no language name ''Tacawit alatin''

I correct the Module by my self. thank you for all.