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  <title>URL Schemes Supported in Lynx</title>
  <link rev="made" href="mailto:lynx-dev@nongnu.org">
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<body>
  <blockquote>
    <em>[</em><a href="#http_url">http, https</a> <em>|</em>
    <a href="#telnet_url">telnet, tn3270, rlogin</a> <em>|</em>
    <a href="#gopher_url">gopher</a> <em>|</em> <a href=
    "#file_url">file</a> <em>|</em> <a href="#ftp_url">ftp</a>
    <em>|</em> <a href="#wais_url">wais</a> <em>|</em> <a href=
    "#news_url">news, nntp, snews</a> <em>|</em> <a href=
    "#newspost_url">newspost, newsreply, snewspost, snewsreply</a>
    <em>|</em> <a href="#mailto_url">mailto</a> <em>|</em> <a href=
    "#finger_url">finger</a> <em>|</em> <a href="#cso_url">cso</a>
    <em>|</em> <a href="#bibp_url">bibp</a> <em>|</em> <a href=
    "#exec_url">lynxexec, lynxprog</a> <em>|</em> <a href=
    "#cgi_url">lynxcgi</a><em>|</em> <a href="#ncftp_url">NcFTP</a>
    <em>|</em> <a href="#internal_url">internal</a><em>]</em>
  </blockquote>

  <h1><em>URL Schemes Supported in Lynx</em></h1>

  <p>Lynx handles a number of URL types, that are enumerated below.
  For more details about URLs (Uniform Resource Locators) see
  <em>RFC1738</em>:</p>

  <ul>
    <li><a href=
    "http://www.w3.org/Addressing/rfc1738.txt">http://www.w3.org/Addressing/rfc1738.txt</a></li>

    <li><a href=
    "ftp://ftp.rfc-editor.org/in-notes/rfc1738.txt">ftp://ftp.rfc-editor.org/in-notes/rfc1738.txt</a></li>
  </ul>

  <p>Lynx resolves partial or relative URLs in documents with
  respect to the BASE if one was specified, otherwise with respect
  to the document's absolute URL, using the rules described in
  <em>RFC1808</em>:</p>

  <ul>
    <li><a href=
    "http://www.w3.org/Addressing/rfc1808.txt">http://www.w3.org/Addressing/rfc1808.txt</a></li>

    <li><a href=
    "ftp://ftp.rfc-editor.org/in-notes/rfc1808.txt">ftp://ftp.rfc-editor.org/in-notes/rfc1808.txt</a></li>
  </ul>and in subsequent drafts of the <em>IETF</em>:

  <ul>
    <li><a href="http://www.ics.uci.edu/pub/ietf/uri/">Uniform
    Resource Identifiers (URI) Working Group</a></li>
  </ul>

  <p>When entering a URL on the command line to be used as the
  <em>startfile</em>, or at the prompt for a '<em>g</em>'oto entry,
  a partial host field can be used and the scheme field can be
  omitted if the scheme and fully qualified domain name can be
  constructed internally by using the URL_DOMAIN_PREFIXES and
  URL_DOMAIN_SUFFIXES definitions in the Lynx configuration file.
  See the explanation of those definitions and their use in your
  <em>lynx.cfg</em>.</p>

  <p>For example, <em>wfbr</em> will be treated as
  <em>http://www.wfbr.edu/</em>, and <em>wfbr/dir/lynx</em> will be
  treated as <em>http://www.wfbr.edu/dir/lynx</em>, but
  <em>gopher.wfbr.edu/11/_fileserv/_lynx</em> will be treated as
  <em>gopher://gopher.wfbr.edu/11/_fileserv/_lynx</em>.</p>

  <p>For files or directories on the local host, a tilde
  (<em>~</em>) is expanded to the path of the account's login
  directory, e.g., <em>~/foo</em> will be expanded to
  <em>file://localhost/your/login/directory/foo</em>. The tilde
  expansion is done homologously on Unix and VMS.</p>

  <p>On VMS, Lynx also will expand any file or directory spec
  recognizable to DCL into a valid URL, e.g., <em>[]</em> will be
  expanded to
  <em>file://localhost/current/default/directory</em>.</p>

  <p>These expansions are <em>SOLELY</em> for <em>startfile</em> or
  '<em>g</em>'oto entries! Any partial or relative URLs within HTML
  documents are resolved according to the rules specified in
  RFC1808 and subsequent IETF drafts.</p>
  <hr>

  <h2><a name="http_url">The <em>http</em> and <em>https</em>
  URLs:</a></h2>

  <p>Lynx handles http URLs exactly as specified in RFC1738. The
  format is:</p>
  <pre>
      <em>http://host:port/path?searchpart#fragment</em>
</pre>where <em>:port</em> is optional and defaults to
<em>:80</em>, <em>/path</em> if present is a slash-separated series
of symbolic elements, and <em>?searchpart</em> if present is the
query for an ISINDEX search or the content of a FORM with
METHOD="GET". The <em>#fragment</em> field if present indicates a
location in the document to seek for display, based on a NAME-ed
anchor or an ID attribute within the document, and is technically
an instruction rather than part of the URL. Lynx will treat ID
attributes as NAME-ed anchors for all tags in the BODY of a
document which can correspond to positions in the rendering of the
document.

  <p>The https URL has the same format, but the default port is
  <em>:443</em>.</p>
  <hr>

  <h2><a name="telnet_url">The <em>telnet</em>, <em>tn3270</em>,
  and <em>rlogin</em> URLs:</a></h2>

  <p>A <em>telnet</em> URL generally results in Lynx spawning a
  telnet session. Lynx implements the complete telnet URL scheme,
  i.e.:</p>
  <pre>
      <em>telnet://user:password@host:port</em>
</pre>

  <p>The <em>user</em> and/or <em>:password</em> fields may be
  omitted, and the <em>@</em> should be omitted if neither is
  present. The port defaults to <em>:23</em> when omitted in the
  URL.</p>

  <p>A <em>tn3270</em> or <em>rlogin</em> URL is specified
  equivalently, and similarly spawns a tn3270 or rlogin session.
  The actual behavior is dependent on the TCP-IP software installed
  on the local and target hosts.</p>

  <p>It is unwise to include the <em>:password</em> field except
  for URLs which point to anonymous or other public access
  accounts, and for most TCP-IP software you will be prompted for a
  password whether or not one was included in the URL.</p>
  <hr>

  <h2><a name="gopher_url">The <em>gopher</em> URL:</a></h2>

  <p>The gopher URL takes the form:</p>
  <pre>
      <em>gopher://host:port/gopher-path</em>
</pre>where <em>:port</em> is optional and defaults to
<em>:70</em>, and the <em>/gopher-path</em> is opaque (not fully
equivalent to the slash-separated series of symbolic elements of
http paths) as explained in RFC1738. Typically, the gopher-path
consists of a <a href=
"keystrokes/gopher_types_help.html"><em>gophertype</em></a>
indicating the file or service type (e.g., <em>0</em> or <em>I</em>
for plain text or an image, respectively, <em>7</em> for a search,
or <em>1</em> for a directory), followed by a platform-specific
<em>selector</em>. Any reserved characters in the selector should
be hex escaped (<em>%hh</em>), including slashes, although hex
escaping of slashes is not required by Lynx in gopher URLs.

  <p>Lynx does not overtly support the gopher+ protocol, and does
  not represent itself as gopher+ capable when communicating with
  gopher servers. Lynx might transmit any
  (hex-escaped-tab-separated) extended gopher+ fields in a URL if
  an author included them in a document, but is likely to mishandle
  what the gopher server returns in such cases, and would not
  generate and transmit them itself. For pre-formed URLs to submit
  gopher searches, it may be better to use a <em>?</em> rather than
  hex-escaped tab (<em>%09</em>) as the separator for the
  <em>searchpart</em> in the <em>selector</em>, e.g.:<br>
  <em>gopher://gopher.wfbr.edu/77/_shell/search.shell%20/_shell/walker?lynx*</em>
  Lynx will handle the <em>%09</em> if you use that instead of
  <em>?</em>, but other WWW clients may mishandle it.</p>

  <p>For the <em>gophertype</em> which signifies HTML (<em>h</em>),
  if the <em>selector</em> begins with <em>GET%20/</em> Lynx will
  convert the gopher URL to an http URL, e.g.:<br></p>
  <pre>
<em>gopher://www.wfbr.edu:80/hGET%20/</em>
</pre>will become:<br>
  <pre>
<em>http://www.wfbr.edu/</em>
</pre>The port field will be retained if it is not <em>:80</em>,
and will default to <em>:70</em> if it was defaulted originally.
These conventions were adopted during development of the University
of Minnesota gopher software to facilitate the offering of links to
MIME-capable http servers in the listings returned by gopher
servers, but should be considered Lynxisms and UMN Gopherisms.
  <hr>

  <h2><a name="file_url">The <em>file</em> URL:</a></h2>

  <p>The file URL is used to retrieve files or generate a directory
  listing on the local host. The host field can be
  <em>localhost</em> or a domain name for the local host:<br></p>
  <pre>
<em>file://localhost/path</em>
</pre>If you do not use <em>localhost</em> or a domain name for the
local host, Lynx will substitute <em>ftp://</em> for
<em>file://</em> and treat it as an ftp URL.

  <p>The <em>/path</em> is treated as originating at the root,
  unless you include a tilde (<em>~</em>), e.g.:</p>
  <pre>
      <em>file://localhost/~/foo</em>   will be converted to:
      <em>file://localhost/your/login/directory/foo</em>
</pre>The latter feature is a Lynxism, is done homologously on Unix
and VMS, and should be used ONLY in local documents intended for
Lynx.

  <p>On VMS, the first element of the path, if not a tilde, is
  assumed to be a device, e.g.:</p>
  <pre>
      <em>file://localhost/www_root/directory/filename.suffix</em>
</pre>should be used for:
<em>www_root:[directory]filename.suffix</em><br>
  If you are unsure how to specify a file URL in local documents on
  VMS, invoke Lynx with the desired file or directory as the
  <em>startfile</em> using any spec acceptable to DCL, and then use
  the <em>showinfo</em> command (<em>=</em>) to see the file URL
  which Lynx created for it.
  <hr>

  <h2><a name="ftp_url">The <em>ftp</em> URL:</a></h2>

  <p>The ftp URL has the general format:</p>
  <pre>
      <em>ftp://host:port/path;type=[D,I, or A]</em>
      <em>ftp://username@host:port/path;type=[D,I, or A]</em>
</pre>

  <p>The default port is <em>:21</em> and the default
  <em>username</em> is <em>anonymous</em>. If <em>username</em> is
  included, Lynx will prompt you for the password. For anonymous
  ftp, Lynx uses your <em>personal_mail_address</em> (user@host) as
  the <em>password</em> if it has been defined via the
  '<em>o</em>'ptions menu. Otherwise, Lynx uses the dummy password
  <em>WWWUser</em>. (A password can also be embedded in the URL, by
  replacing <em>username</em> with <em>username:password</em>. This
  is strongly discouraged for 'real' passwords that must be kept
  secret, since URLs with the completely unencrypted
  <em>password</em> may show up on the screen, in HISTORY and LIST
  pages etc., and may even become visible to remote sites for
  example through Referer headers.) Do not include the <em>@</em>
  if neither <em>username</em> nor <em>:password</em> is
  included.</p>

  <p>The <em>;type=</em> parameter can be used with value
  <em>D</em>, <em>I</em>, or <em>A</em> to force handling of the
  URL as, respectively, a directory listing, binary file, or ASCII
  file. The Lynx ftp gateway normally determines this itself, but
  the parameter can be used if the internal procedure draws an
  incorrect inference about the nature of the ftp URL.</p>

  <p>The <em>/path</em> is treated according to RFC1738 for VMS and
  VM/CMS ftp servers. The lead slash (<em>/</em>) is treated purely
  as a separator, not as a designator for the root, and the
  <em>path</em> string if present is treated as in or under the
  login directory. For VMS ftp servers, if you wish to have the
  first element treated as a device rather than file or
  subdirectory name, begin it with a hex-escaped slash
  (<em>%2f</em>), e.g.:</p>
  <pre>
      <em>ftp://user@myhost/%2fsys$common/syshlp</em>
</pre>can be used for a listing of sys$common:[syshlp]<br>
  Also, on VM/CMS ftp servers, if the <em>path</em> string begins
  with <em>vmsysu%3a</em> it receives special handling as an SFS
  path, e.g.:
  <pre>
      <em>ftp://ubvm.cc.buffalo.edu/vmsysu%3alistserv.webshare</em>
</pre>

  <p>For Unix and Unix-emulation ftp servers, RFC1738 is not
  respected and the lead slash is treated as the root, i.e., the
  <em>/path</em> is handled equivalently to that in file URLs. The
  distinction is irrelevant for anonymous ftp, but matters when
  using ftp for non-anonymous accounts. If you are using ftp with a
  Unix server and do wish to get a listing of the login directory
  or have the <em>path</em> string treated as a file or path under
  the login directory, include a tilde (<em>~</em>) as for <a href=
  "#file_url">file</a> URLs, e.g.:</p>
  <pre>
      <em>ftp://user@myhost/~</em>
</pre>
  <hr>

  <h2><a name="wais_url">The <em>wais</em> URL:</a></h2>

  <p>The wais URL is used to retrieve resources using the Wide Area
  Information System protocol. The format is:</p>
  <pre>
      <em>wais://host:port/database</em>
      <em>wais://host:port/database?wais_query</em>
      <em>wais://host:port/database/wais_type/wais_path</em>
</pre>where <em>:port</em> defaults to <em>:210</em>

  <p>Direct wais support is built into Lynx for VMS, and can be
  compiled into Lynx on Unix.</p>

  <p>If only a <em>database</em> is indicated in the URL, Lynx
  returns an ISINDEX cover page for searching that
  <em>database</em>, and will submit your search with the
  <em>wais_query</em> appended. Lynx will convert the server's
  reply into a hit list with URLs that include the
  <em>wais_type</em> and <em>wais_path</em> for retrieving items
  from the hit list.</p>
  <hr>

  <h2><a name="news_url">The <em>news</em>, <em>nntp</em>, and
  <em>snews</em> URLs:</a></h2>

  <p>The news and nntp URLs are handled by Lynx as specified in
  RFC1738, but for compatibility with other clients, Lynx allows
  inclusion of host and port fields in news URLs, which properly
  should be used <em>only</em> in nntp and snews URLs. If not
  included in news URLs, Lynx will use the nntp server pointed to
  by the NNTPSERVER environment variable or configuration symbol
  (see lynx.cfg), with default port <em>:119</em>. A host field
  must be included in nntp URLs, and the port field is optional
  with the same default.</p>

  <p>If the URL requires authentication, lynx will prompt you for
  the username and password. These are cached during a session, for
  reuse on the same host. If $HOME/.newsauth exists, lynx
  initializes its cache from this file. The .newsauth file contents
  are one line per entry: hostname, password and username (in that
  order) separated by a space.</p>

  <p>The formats are:<br></p>
  <pre>
      <em>news:newsgroup</em> (retrieves list of messages in newsgroup)
      <em>news:messageID</em> (retrieves the message)
      <em>news:*</em> (retrieves list of all available newsgroups)
      <em>nntp://host:port/newsgroup</em>
      <em>nntp://host:port/messageID</em>
      <em>nntp://host:port/*</em>
</pre>(snews same as nntp, but the default port is <em>:563</em>)

  <p>The <em>messageID</em> is the message's unique identifier,
  consisting of an identification string and the host of origin for
  the message (<em>ident_string@origin_host</em>).</p>

  <p>Lynx also supports wildcarding via an asterisk for listings of
  news hierarchies or sub-hierarchies, e.g.:</p>
  <pre>
      <em>news:comp.infosystems.*</em>
      <em>nntp://host:port/comp.infosystems.*</em>
</pre>(snews same as nntp, but the default port is
<em>:563</em>)<br>
  This is not in RFC1738 and may not be supported by all other
  clients.

  <p>Lynx allows you both to <em>reply</em> to the author of a news
  message via email, and, if news posting has been enabled, to send
  a <em>followup</em> message to the newsgroup (see <a href=
  "#newspost_url">newspost, newsreply, snewspost,
  snewsreply</a>).</p>

  <p>Lynx converts any strings in news messages which appear to be
  a URL with a supported scheme into a link for accessing that
  URL.</p>

  <p>Lynx also supports the newsgroup and message number URL
  scheme:<br></p>
  <pre>
      <em>news:newsgroup/startNo-endNo</em> (lists message range in newsgroup)
      <em>news:newsgroup/messageNo</em>     (retrieves the message by number)
      <em>nntp://host:port/newsgroup/startNo-endNo</em>
      <em>nntp://host:port/newsgroup/messageNo</em>
</pre>(snews same as nntp, but the default port is
<em>:563</em>)<br>
  Use of this scheme is not recommended, because the message
  numbers are specific to each nntp server, unlike the unique
  identifiers for news messages.
  <hr>

  <h2><a name="newspost_url">The <em>newspost</em>,
  <em>newsreply</em>, <em>snewspost</em>, and <em>snewsreply</em>
  URLs:</a></h2>

  <p>When Lynx receives group listings or articles via
  <em>news</em>, <em>nntp</em> or <em>snews</em> URLs, it also
  checks whether the nntp server supports posting from the Lynx
  user's site, and if so, includes links for posting new messages
  to that server, or for posting followups (replies) to previously
  posted messages. RFC1738, and IETF URL drafts through this
  release of Lynx, do not include any schemes for posting to news
  groups. Lynx has long supported newspost and newreply URL schemes
  for posting new messages or sending followups, respectively, to
  standard nntp servers, with default port <em>:119</em>. Lynx now
  also supports homologous snewspost and snewsreply URLs for use
  with SSL capable nntp servers.</p>

  <p>The formats are:</p>
  <pre>
      <em>newspost://host:port/newsgroup(s)</em>  (post a new message)
      <em>newsreply://host:port/newsgroup(s)</em> (post a followup message)
</pre>(snewspost and snewsreply have the same formats, but the
default port is <em>:563</em>)

  <p>If the host field is omitted, it defaults to that pointed to
  by the NNTPSERVER configuration or environmental variable.
  Inclusion of at least one newsgroup in the URL is required, and
  additional groups can be specified as a comma-separated list.
  Wildcarding of newsgroup names is not supported for these URLs.
  For newsreply and snewsreply URLs, if an external editor has been
  defined via the <em>Options Menu</em>, the user is offered an
  option to include the currently displayed document, which
  presumably is a news article with a <em>followup</em> link that
  was activated, and if confirmed, each line of that document is
  prefixed with a right-angle-bracket. The user is expected to edit
  such an inclusion so that only the passages relevant to the
  followup message are retained.</p>

  <p>These URLs can be used as command line startfiles (in which
  case, Lynx will exit after posting the message, and the newreply
  or snewsreply URLs degrade to newspost or snewpost URLs,
  respectively). They also can be used as HREF attribute values in
  any HTML document homologously to <a href=
  "#mailto_url">mailto</a> URLs, with the qualification that they
  presently are supported only by Lynx.</p>
  <hr>

  <h2><a name="mailto_url">The <em>mailto</em> URL:</a></h2>

  <p>The mailto URL is used to provide links that when activated
  can be used to send a comment or the content of a FORM to an
  Internet email address (user@host). The format is:</p>
  <pre>
      <em>mailto:user@host</em>
</pre>

  <p>The description of the mailto URL in RFC1738 has been
  interpreted by some as allowing only a single recipient, but Lynx
  invented the mailto URL, has always supported a series of
  user@host addresses as a comma-separated list, and still does.
  For compatibility with Explorer, Lynx also accepts a
  semi-colon-separated list.</p>

  <p>For compatibility with Netscape, Lynx parses any
  <em>?subject=The%20Subject</em> appended to the URL, trims the
  URL at the <em>?</em>, and uses the value as the default Subject:
  for the message or FORM content mailing. This is not recommended
  practice. The preferred way to indicate the default Subject: for
  a LINK or Anchor with a mailto HREF, or a FORM with a mailto
  ACTION, is via a TITLE attribute with the subject string as its
  value, e.g.:</p>
  <pre>
      <em>&lt;LINK REV="made"
            HREF="mailto:me@myhost,her@herhost" TITLE="The Subject"&gt;</em>

      <em>&lt;A HREF="mailto:user@host" TITLE="The Subject"&gt;...&lt;/A&gt;</em>

      <em>&lt;FORM METHOD="post" ENCTYPE="text/plain"
            ACTION="mailto:WebMaster@host" TITLE="The Subject"&gt;
       ...
      &lt;/FORM&gt;</em>
</pre>

  <p>Note that a TITLE attribute for FORM is now included in the
  HTML specifications. Some clients use a SUBJECT attribute for
  this purpose in FORM tags, and Lynx recognizes that as a synonym
  for TITLE.</p>

  <p>Lynx also will process any <em>to=address(es)</em>,
  <em>cc=address(es)</em>, <em>keywords=word_list</em> and/or
  <em>body=message</em> fields in <em>?searchpart</em> tack-ons to
  mailto URLs. The <em>to</em> and/or <em>cc</em> values can be
  single addresses, or comma- or semi-colon-separated lists of
  addresses. All addresses, and any <em>body</em> values, will be
  offered for approval by the user before proceeding with a
  mailing. Any other name=value pairs in the <em>?searchpart</em>
  will be ignored. Also, if the mailto URL is the ACTION for a
  FORM, any <em>body</em> in a <em>?searchpart</em> tack-on will be
  ignored, because the body of the mailing must be constructed
  solely from the the FORM's content. Lynx expects multiple
  name=value pairs in a <em>?searchpart</em> tack-on to be
  separated by ampersands, as in the original Netscape
  implementation, and in an equally ill-advised IETF draft of that
  implementation (<a href=
  "ftp://ftp.isi.edu/internet-drafts/draft-hoffman-mailto-url-03.txt">draft-hoffman-mailto-url-03.txt</a>).
  These should be represented as entities (<em>&amp;amp;</em>) in
  the HTML markup. This functionality is generally desired, but the
  IETF backward compatibility principal normally would lead to a
  new scheme being used (e.g., <em>mail:</em>, or <em>smtp:</em>),
  rather than breaking <em>mailto:</em> implementations.</p>

  <p>If <em>ENCTYPE="text/plain"</em> is specified for a FORM with
  a mailto ACTION, Lynx will not hex escape the name=value pairs of
  the FORM's content, and will use physical newlines instead of
  '<em>&amp;</em>' or '<em>;</em>' to separate the pairs, so that
  the content will be readable directly. Otherwise, Lynx will mail
  the content with the default:</p>
  <pre>
      <em>ENCTYPE="application/x-www-form-urlencoded"</em> ('<em>&amp;</em>' separates pairs)
</pre>or:
  <pre>
      <em>ENCTYPE="application/sgml-form-urlencoded"</em> ('<em>;</em>' separates pairs)
</pre>if the latter was indicated.

  <p>Note that when mailing FORM content Lynx wraps any lines
  longer than 78 characters, to avoid buffer overflows in mail
  software and to ensure reliable transmission across gateways. If
  the ENCTYPE was not <em>text/plain</em>, any script which decodes
  the mailed content should ignore the physical newlines and
  recognize only hex escaped newline characters as intended to be
  present in the decoded content.</p>

  <p>If the mailto URL is not the ACTION for a FORM, and if an
  external editor has been defined via the <em>Options Menu</em>,
  the user is offered an option to include the currently displayed
  document. If this option is accepted, each line of that document
  is prefixed with a right-angle-bracket, and the prefixed
  inclusion should be trimmed by the user to just those passages
  relevant to the message which will be sent.</p>
  <hr>

  <h2><a name="finger_url">The <em>finger</em> URL:</a></h2>

  <p>Lynx has full support for the finger protocol, but a format
  for finger URLs has not yet been adopted by the IETF. The formats
  supported by Lynx therefore include every possibility not
  inconsistent with RFC1738, including:</p>
  <pre>
      finger://host                         finger://@host
      finger://host/                        finger://@host/
      finger://host/%2fw                    finger://@host/w
      finger://host/w                       finger://host/w/
      finger://host/username[@host]         finger://username@host
      finger://host/username[@host]/        finger://username@host/
      finger://host/w/username[@host]       finger://username@host/w
      finger://host/%2fw%20username[@host]  finger://host/username[@host]/w
      finger://host/w/username
</pre>

  <p>Activating a finger URL will send a request to the finger
  server via port 79 on the host specified. You can include
  <em>:79</em> in the URL, but no other value is allowed. The
  <em>/w</em> or <em>/%2fw</em> is used to request a full report
  for finger servers which support it, and is not case sensitive
  (i.e., can be <em>/W</em> or <em>/%2fW</em>). Any strings in the
  report which appear to be a URL with a supported scheme will be
  converted into a link for accessing that URL.</p>

  <p>An alternative way to access finger servers is via gopher URLs
  with port 79 and the plain text (<em>0</em>) <em>gophertype</em>
  specified:<br>
  <em>gopher://host:79/0</em><br>
  Lynx will handle such URLs equivalently to overt finger URLs,
  including creation of links for any strings which appear to be
  supported URLs.</p>
  <hr>

  <h2><a name="cso_url">The <em>cso</em> URL:</a></h2>

  <p>The cso URL is intended to provide a gateway to CSO/PH (QI)
  servers. The requests are made on port 105 by default
  (<em>:105</em>), with the following overt cso URL format:<br></p>
  <pre>
      <em>cso://host</em>
</pre>

  <p>You also can use a gopher URL format with port 105 and the CSO
  (<em>2</em>) <em>gophertype</em> specified:</p>
  <pre>
      <em>gopher://host:105/2</em>
</pre>

  <p>Lynx will parse the stream returned by the server for the
  above URLs and create a FORM for submitting additional requests
  (searches) to the server. Any strings in the reports returned for
  these requests (searches) which appear to be a URL with a
  supported scheme will be converted into a link for accessing that
  URL.</p>
  <hr>

  <h2><a name="bibp_url">The <em>bibp</em> URL:</a></h2>

  <p>Lynx provides built-in support for bibliographic protocol
  (BibP). BibP links are links to published works such as books or
  journal articles, without a predefined server. BibP links are
  intended for resolution by a local bibhost server
  (http://bibhost/) if it exists. Otherwise, resolution is
  performed by a document-specified server or a known global
  server.</p>

  <h2><a name="exec_url">The <em>lynxexec</em> and
  <em>lynxprog</em> URLs:</a></h2>

  <p>If execution of spawned commands has been enabled in your Lynx
  image, the lynxexec and lynxprog URLs can be used to execute
  arbitrary system commands or invoke system utilities. Any system
  command and associated switches or qualifiers can be used, with
  the syntax appropriate for a shell running Lynx on Unix, or for
  DCL on VMS, e.g.:</p>
  <pre>
      <em>lynxexec:dir/date/size foo:[blah]</em> (VMS)
      <em>lynxexec:ls -l /foo/blah</em>          (Unix)
      <em>lynxprog:news</em>
</pre>(Note, however, that restrictions on acceptable commands or
utilities may be imposed by the system administrator.)

  <p>You optionally can include <em>//localhost/</em> in the URL,
  between the scheme field and the command, but that is always
  implied. The lynxexec and lynxprog URLs differ only in that with
  lynxexec you are prompted to enter <em>RETURN</em> before Lynx
  clears the screen and restores the previously displayed document,
  so that you can read any screen output generated by the spawned
  command, whereas no such pause is imposed upon exit from the
  utility invoked via lynxprog.</p>

  <p>These are Lynxisms and should be used only in local documents
  intended solely for Lynx.</p>
  <hr>

  <h2><a name="cgi_url">The <em>lynxcgi</em> URL:</a></h2>

  <p>The lynxcgi URL is implemented only on Unix, can be used as
  the ACTION for a FORM, and if enabled in your Lynx image has the
  format:</p>
  <pre>
      <em>lynxcgi://localhost/path_to_CGI_script</em>
</pre>where <em>//localhost</em> is optional and always implied;
the full path should be specified, as `~' is not recognized; if the
script is in the directory Lynx was started from, the simple file
name is adequate. The output of the script should be text/html and
is rendered and displayed by Lynx. Restrictions on use of lynxcgi
and on acceptable paths can be imposed in <em>userdefs.h</em> and
<em>lynx.cfg</em>, qv.

  <p>This is a Lynxism and should be used only in local documents
  intended solely for Lynx, or for limited local testing of CGI
  scripts without an http server.</p>
  <hr>

  <h2><a name="ncftp_url">The <em>NcFTP</em> URL:</a></h2>

  <p>Lynx recognizes the NcFTP-style ftp URL, e.g.,</p>
  <pre>
        <cite>ftpHost</cite>:<cite>fileSpecification</cite>
</pre>for example
  <pre>
<code>
        ftp.gnu.org:/pub/gnu
</code>
</pre>
  <hr>

  <h2><a name="internal_url">The <em>LYNXfoo</em> internal
  URLs:</a></h2>

  <p>Lynx uses a variety of private URL schemes for communication
  among its internal modules. They start with uppercase letters
  <code>LYNX</code> by convention, although, as input, URL schemes
  are recognized in a case-insensitive manner.</p>

  <p>As you discover what they are, and are tempted to use them
  externally in documents, you should <em>resist</em> that
  temptation:</p>

  <ul>
    <li>There already is too much browser-specific markup
    around...</li>

    <li>The schemes, or their meanings, may change between Lynx
    versions.</li>

    <li>Even if a scheme stays the same, some aspect of its
    behavior may be modified without notice, or the context in
    which it is allowed may change.</li>

    <li>If it doesn't work as expected when used outside of the
    intended purpose, don't expect anyone to "fix" it.</li>
  </ul>

  <p>For example, tempting though it might be, do not use
  these:</p>
  <pre>
      <em>Return to your &lt;A HREF="LYNXHIST:0"&gt;Startfile&lt;/A&gt;</em>
      <em>Review your &lt;A HREF="LYNXKEYMAP:"&gt;Keymap&lt;/A&gt;</em>
</pre>(No, they won't do any harm. Yes, they work. But don't rely
on it.)

  <p>If you must try one, the second is OK from the command
  line:<br></p>
  <pre>
      <em>lynx LYNXKEYMAP:</em>
</pre>But within Lynx, use the '<em>K</em>' keystroke command.
Sometimes it may be convenient to use a private scheme with
'<em>g</em>'oto, as in:
  <pre>
      <em>g LYNXMESSAGES:</em>
      <em>g LYNXCOMPILEOPTS:</em>
      <em>g LYNXCFG:</em>
</pre>But again, there usually is a way in which those special
pages are meant to be reached that is more convenient.
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