The mapping for URIs onto some existing
standard and experimental protocols
is outlined in the BNF syntax definition
. Notes on particular protocols
follow. These URIs are frequently
referred to as URLs, though the exact
definition of the term URL is still
under discussion (March 1993). The
schemes covered are:
- http
- Hypertext Transfer Protocol
(examples)
- ftp
- File Transfer protocol
- gopher
- Gopher protocol
- mailto
- Electronic mail address
- news
- Usenet news
- telnet , rlogin and tn3270
- Reference
to interactive sessions
- wais
- Wide Area Information Servers
- file
- Local file access
The following schemes are proposed
as essential to the unification of
the web with electronic mail, but
not currently (to the author's knowledge)
implemented:
- mid
- Message identifiers for electronic
mail
- cid
- Content identifiers for MIME
body part
The schemes for x.500, network management
database, and whois++ have not been
specified and may be the subject
of further study. Schemes for Prospero
, and restricted NNTP use are not
currently implemented as far as the
author is aware.
The "urn" prefix is reserved for
use in encoding a Uniform Resource
Name when that has been developed
by the IETF working group.
New schemes may be registered at
a later time.