Internet.

   A file URL takes the form:

       file:///

   where  is the fully qualified domain name of the system on
   which the  is accessible, and  is a hierarchical
   directory path of the form //.../.

   For example, a VMS file

     DISK$USER:[MY.NOTES]NOTE123456.TXT

   might become

     <URL:file://vms.host.edu/disk$user/my/notes/note12345.txt>

   As a special case,  can be the string "localhost" or the empty
   string; this is interpreted as `the machine from which the URL is
   being interpreted'.

   The file URL scheme is unusual in that it does not specify an
   Internet protocol or access method for such files; as such, its
   utility in network protocols between hosts is limited.

3.11 PROSPERO

   The Prospero URL scheme is used to designate resources that are
   accessed via the Prospero Directory Service. The Prospero protocol is
   described elsewhere [14].

   A prospero URLs takes the form:

      prospero://:/;=

   where  and  are as described in Section 3.1. If :
   is omitted, the port defaults to 1525. No username or password is




 
RFC 1738            Uniform Resource Locators (URL)        December 1994


   allowed.

   The  is the host-specific object name in the Prospero
   protocol, suitably encoded.  This name is opaque and interpreted by
   the Prospero server.  The semicolon ";" is reserved and may not
   appear without quoting in the .

   Prospero URLs are interpreted by contacting a Prospero directory
   server on the specified host and port to determine appropriate access
   methods for a resource, which might themselves be represented as
   different URLs. External Prospero links are represented as URLs of
   the underlying access method and are not represented as Prospero
   URLs.

   Note that a slash "/" may appear in the  without quoting and
   no significance may be assumed by the application.  Though slashes
   may indicate hierarchical structure on the server, such structure is
   not guaranteed. Note that many s begin with a slash, in
   which case the host or port will be followed by a double slash: the
   slash from the URL syntax, followed by the initial slash from the
   . (E.g., <URL:prospero://host.dom//pros/name> designates a
    of "/pros/name".)

   In addition, after the , optional fields and values
   associated with a Prospero link may be specified as part of the URL.
   When present, each field/value pair is separated from each other and
   from the rest of the URL by a ";" (semicolon).  The name of the field
   and its value are separated by a "=" (equal sign). If present, these
   fields serve to identify the target of the URL.  For example, the
   OBJECT-VERSION field can be specified to identify a specific version
   of an object.

4. REGISTRATION OF NEW SCHEMES

   A new scheme may be introduced by defining a mapping onto a
   conforming URL syntax, using a new prefix. URLs for experimental
   schemes may be used by mutual agreement between parties. Scheme names
   starting with the characters "x-" are reserved for experimental
   purposes.

   The Internet Assigned Numbers Authority (IANA) will maintain a
   registry of URL schemes. Any submission of a new URL scheme must
   include a definition of an algorithm for accessing of resources
   within that scheme and the syntax for representing such a scheme.

   URL schemes must have demonstrable utility and operability.  One way
   to provide such a demonstration is via a gateway which provides
   objects in the new scheme for clients using an existing protocol.  If




 
RFC 1738            Uniform Resource Locators (URL)        December 1994