stac-spec

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Dear all, I was wondering if you have already considered how to describe keywords from different "categories".

At the moment it is only possible to add keywords as strings, no matter what the keywords are about. But it would be helpful to be able to assign them to a specific category as for example :

• spatial keywords: "World", "Europe", "Antarctica" etc.
• temporal keywords: "daily", "8-day", "yearly"
• thematic keywords: "Land user", "Elevation" etc.

Something like {"category":"temporal", "value":"daily"}

I've got a STAC catalog where I want to give the possibility to apply some filters for searching between the collections, but having all the keywords together as simple strings makes it impossible to make a sort of faceted search on keywords from different domains. I can just have a flat list of keywords that is kind of hard to use since all terms are mixed up.

+1 ideally this property could be defined with an IRI and be called "scheme"

I remember some discussions about this in the past, but we obviously decided for the "simple" approach. Categories in STAC are more like a simple list of tags, not what others might understand when talking about keywords with different vocabularies etc. I've seen people do something like ["temporal:yearly". "thematic:elevation", ...] though.

Having that said, your proposal would likely need a new STAC extension.

Please check and review https://github.com/stac-extensions/subjects and let me know if it covers the need here

Please see https://github.com/stac-extensions/themes