For example, the URL <URL:ftp://myname@host.dom/%2Fetc/motd> is
   interpreted by FTP-ing to "host.dom", logging in as "myname"
   (prompting for a password if it is asked for), and then executing
   "CWD /etc" and then "RETR motd". This has a different meaning from
   <URL:ftp://myname@host.dom/etc/motd> which would "CWD etc" and then
   "RETR motd"; the initial "CWD" might be executed relative to the
   default directory for "myname". On the other hand,
   <URL:ftp://myname@host.dom//etc/motd>, would "CWD " with a null
   argument, then "CWD etc", and then "RETR motd".

   FTP URLs may also be used for other operations; for example, it is
   possible to update a file on a remote file server, or infer
   information about it from the directory listings. The mechanism for
   doing so is not spelled out here.

3.2.3. FTP Typecode is Optional

   The entire ;type= part of a FTP URL is optional. If it is
   omitted, the client program interpreting the URL must guess the
   appropriate mode to use. In general, the data content type of a file
   can only be guessed from the name, e.g., from the suffix of the name;
   the appropriate type code to be used for transfer of the file can
   then be deduced from the data content of the file.

3.2.4 Hierarchy

   For some file systems, the "/" used to denote the hierarchical
   structure of the URL corresponds to the delimiter used to construct a
   file name hierarchy, and thus, the filename will look similar to the
   URL path. This does NOT mean that the URL is a Unix filename.

3.2.5. Optimization

   Clients accessing resources via FTP may employ additional heuristics
   to optimize the interaction. For some FTP servers, for example, it
   may be reasonable to keep the control connection open while accessing
   multiple URLs from the same server. However, there is no common
   hierarchical model to the FTP protocol, so if a directory change
   command has been given, it is impossible in general to deduce what
   sequence should be given to navigate to another directory for a
   second retrieval, if the paths are different.  The only reliable
   algorithm is to disconnect and reestablish the control connection.








 
RFC 1738            Uniform Resource Locators (URL)        December 1994


3.3. HTTP

   The HTTP URL scheme is used to designate Internet resources
   accessible using HTTP (HyperText Transfer Protocol).

   The HTTP protocol is specified elsewhere. This specification only
   describes the syntax of HTTP URLs.

   An HTTP URL takes the form:

      http://:/?

   where  and  are as described in Section 3.1. If :
   is omitted, the port defaults to 80.  No user name or password is
   allowed.   is an HTTP selector, and  is a query
   string. The  is optional, as is the  and its
   preceding "?". If neither  nor  is present, the "/"
   may also be omitted.

   Within the  and  components, "/", ";", "?" are
   reserved.  The "/" character may be used within HTTP to designate a
   hierarchical structure.

3.4. GOPHER

   The Gopher URL scheme is used to designate Internet resources
   accessible using the Gopher protocol.

   The base Gopher protocol is described in RFC 1436 and supports items
   and collections of items (directories). The Gopher+ protocol is a set
   of upward compatible extensions to the base Gopher protocol and is
   described in [2]. Gopher+ supports associating arbitrary sets of
   attributes and alternate data representations with Gopher items.
   Gopher URLs accommodate both Gopher and Gopher+ items and item
   attributes.

3.4.1. Gopher URL syntax

   A Gopher URL takes the form:

      gopher://:/<gopher-path>

   where <gopher-path> is one of

       
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