Remove the Metadata.Topic property and use the UsageContext property already defined in the base (Canonical) interface.

It appears that topic is just a usage context without an axis to indicate which way it is being sliced. If you really want that, just make the axis for the usage context optional?

Or add a specific code to the usage context which is for the general category/topic.

This would then lead to better locating of content using the existing context search parameter which is agnostic to code (making it effectively like a topic anyway)

At a minimum provide additional guidance on why you would use the topic in place of the coding in UsageContext.

As discussed on zulip

https://chat.fhir.org/#narrow/stream/179280-fhir.2Finfrastructure-wg/topic/Metadata.20Topic.20.2F.20Canonical.20UsageContext

The descriptions are very close to the same too.

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate title instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

vs

Descriptive topics related to the content of the title. Topics provide a high-level categorization as well as keywords for the title that can be useful for filtering and searching.

Repositories must be able to determine how to categorize the title so that it can be found by topical and keyword searches.

This element provides topical categorization and keywords for the title, as opposed to the more structured context-of-use information provided in the useContext element