Multi-language support: add a property "language" to common metadata

[p1d1d1]

Is there any discussion on adding a new "language" property to the common metadata? This would really support/enable several use cases.

[m-mohr]

Discussion started in stac-extensions/file#12
Related issue in STAC API: radiantearth/stac-api-spec#306
OGC APIs define the langauge keyword: http://docs.ogc.org/DRAFTS/20-004.html#collections-properties-table

I think language would be a useful addition to common metadata and further help with OGC API alignment. It's a non-breaking addition for v1.1.

As part of common metadata, it would be applicable to different contexts, comparable to "created" and updated" for example:

• language in Item properties / Collection -> metadata language
• language in assets -> file language
• language in links -> language of what is linked to
• ...

@p1d1d1 I think it would help to convince people if you could describe what use cases you are thinking about. Also, an "reference" implementation would help as well.

[p1d1d1]

I'm working for the Swiss Government and we are currently using STAC for both raster and vector data: https://data.geo.admin.ch/api/stac/v0.9/
Now, Switzerland is a multilingual country and we have to support at least "de" and "fr" in all services that we provide.
We think that the STAC ecosystem is currently missing a generic multilingual support and to achieve it one would need:

1. Multi-language support: add a property "language" to common metadata #1190
2. Multi-language support stac-api-spec#306
3. Multilingual support stac-browser#123

Or do you see it differently?

A second use case / requirement we have is about the "data language" (asset file). For some datasets in our catalog, we provide Asset files (for the same Item) in different languages and we want to communicate to the user the language in which any textual information in the file is expressed. To achieve this we are currently using our self-defined extension: e.g. https://data.geo.admin.ch/api/stac/v0.9/collections/ch.bav.haltestellen-oev/items/haltestellen-oev

[m-mohr]

I've written a proposal for a new STAC extension that adds multi-language abilities to static STAC collections:
https://github.com/stac-extensions/language

There's also a proposal for a new STAC API extension:
https://github.com/stac-api-extensions/language

Feedback on both would be appreciated in the corresponding issue trackers.