URL
A URL in MusicBrainz is a specific entity representing a regular internet Uniform Resource Locator. A MusicBrainz URL entity can be edited to change the underlying internet URL it points to; and can be linked to Areas, Artists, Events, Instruments, Labels, Places, Recordings, Releases, Release Groups, and Series.
Take a look at the relationship table on the MusicBrainz server to see all types.
You must be a Relationship Editor to change these definitions.