OAuth2 Code Grant RFC has no mention of "audience"


I’ve had a search for OAuth2 and audience but not found any existing topics.

The docs for implementing OAuth2 Code Grant for accessing JIRA REST APIs state that audience is a required field (as is prompt, but I’ve found not having prompt doesnt seem to be a problem). But this isnt mentioned in the RFC on OAuth2 Code Grant

This causes a problem when creating a generic OAuth2 Code Grant integration service as I currently am as it then means you have to allow for the URL of the /auth call to be configurable so people can add audience, something I’ve not found any other Code Grant provider has done (tested a lot of services with this feature).

Is there a reason this was added / could it ever be removed in future to keep the auth pattern more standard?