"additional reference information to be interpreted by the user agent after the retrieval action has been successfully completed" per [URI98] 4.1. Fragment Identifier obsoletes: Relative URL spec, June 1995 revises: Fragment-id in RFC1630, June 1994
In computer hypertext, a fragment identifier is a short string of characters that refers to a resource that is subordinate to another, primary resource. The primary resource is identified by a Uniform Resource Identifier (URI), and the fragment identifier points to the subordinate resource. Typically, the fragment identifier is appended to the Uniform Resource Locator (URL —a type of URI) for a hypertext document and is meant to identify a portion of that document.