A fragment is part of a URL, and typically refers to a fragment identifier at the end of a URL preceded by a # but may also refer to a media fragment which may use a fragment identifier or a query string.
Webmention and fragments
This likely makes sense to document explicitly as a Webmention extension, i.e.:
- Webmention Fragment support
- How and when a webmention sender should use a fragment in the source and or target URLs
- How should a webmention receiver handle a fragment in the source and or target URLs
Where a fragment could be: