Docs requested: More clarity required for Breadcrumbs Interface

I’m writing a Haskell SDK for Sentry and am implementing the breadcrumbs interface. Looking at the docs at https://develop.sentry.dev/sdk/event-payloads/breadcrumbs/ and the Breadcrumb Types section therein, the following points are not clear:

  1. Can type be only ONE OF default, debug, error, navigation, http, info, query, user, or can it be anything else?
  2. What are the possible values of the category field?
  3. What is the relationship between type and category fields?
  4. What does category: started mean? Is there also a special category: ended?
  5. Is category: ui.click special? What about ui.tap, ui.pinch, ui.zoom, etc?
  6. Is there an overlap between the Breadcrumbs and the APM interface?

For reference, there’s an issue discussing some of these points: Breadcrumbs documentation for device events · Issue #213 · getsentry/develop · GitHub