======================================================================
= Gopher (protocol) =
======================================================================
Introduction
======================================================================
The Gopher protocol () is a communication protocol designed for
distributing, searching, and retrieving documents in Internet Protocol
networks. The design of the Gopher protocol and user interface is
menu-driven, and presented an alternative to the World Wide Web in its
early stages, but ultimately fell into disfavor, yielding to Hypertext
Transfer Protocol (HTTP). The Gopher ecosystem is often regarded as
the effective predecessor of the World Wide Web.
Usage
======================================================================
The Gopher protocol was invented by a team led by Mark P. McCahill at
the University of Minnesota. It offers some features not natively
supported by the Web and imposes a much stronger hierarchy on the
documents it stores. Its text menu interface is well-suited to
computing environments that rely heavily on remote text-oriented
computer terminals, which were still common at the time of its
creation in 1991, and the simplicity of its protocol facilitated a
wide variety of client implementations. More recent Gopher revisions
and graphical clients added support for multimedia.
File:Gopher in Firefox 1.5.png|Firefox 1.5 (2005)
Gopher's hierarchical structure provided a platform for the first
large-scale electronic library connections. The Gopher protocol is
still in use by enthusiasts, and although it has been almost entirely
supplanted by the Web, a small population of actively-maintained
servers remains.
Origins
=========
The Gopher system was released in mid-1991 by Mark P. McCahill, Farhad
Anklesaria, Paul Lindner, Daniel Torrey, and Bob Alberti of the
University of Minnesota in the United States. Its central goals were,
as stated in :
* A file-like hierarchical arrangement that would be familiar to
users.
* A simple syntax.
* A system that can be created quickly and inexpensively.
* Extensibility of the file system metaphor; allowing addition of
searches for example.
Gopher combines document hierarchies with collections of services,
including WAIS, the Archie and Veronica search engines, and gateways
to other information systems such as File Transfer Protocol (FTP) and
Usenet.
The general interest in campus-wide information systems (CWISs) in
higher education at the time, and the ease of setup of Gopher servers
to create an instant CWIS with links to other sites' online
directories and resources, were the factors contributing to Gopher's
rapid adoption.
The name was coined by Anklesaria as a play on several meanings of the
word "gopher". The University of Minnesota mascot is the gopher, a
gofer is an assistant who "goes for" things, and a gopher burrows
through the ground to reach a desired location.
Decline
=========
The World Wide Web was in its infancy in 1991, and Gopher services
quickly became established. By the late 1990s, Gopher had ceased
expanding. Several factors contributed to Gopher's stagnation:
* In February 1993, the University of Minnesota announced that it
would charge licensing fees for the use of its implementation of the
Gopher server. Users became concerned that fees might also be charged
for independent implementations. Gopher expansion stagnated, to the
advantage of the World Wide Web, to which CERN disclaimed ownership.
In September 2000, the University of Minnesota re-licensed its Gopher
software under the GNU General Public License.
* Gopher client functionality was quickly duplicated by the early
Mosaic web browser, which subsumed its protocol.
* Gopher has a more rigid structure than the free-form HyperText
Markup Language (HTML) of the Web. Every Gopher document has a defined
format and type, and the typical user navigates through a single
server-defined menu system to get to a particular document. This can
be quite different from the way a user finds documents on the Web.
* Failure to follow the open systems model and bad publicity in
comparison to the World Wide Web
Gopher remains in active use by its enthusiasts, and there have been
attempts to revive Gopher on modern platforms and mobile devices. One
attempt is The Overbite Project, which hosts various browser
extensions and modern clients.
Server census
===============
*, there remained about 160 gopher servers indexed by Veronica-2,
reflecting a slow growth from 2007 when there were fewer than 100.
They are typically infrequently updated. On these servers Veronica
indexed approximately 2.5 million unique selectors. A handful of new
servers were being set up every year by hobbyists with over 50 having
been set up and added to Floodgap's list since 1999. A snapshot of
Gopherspace in 2007 circulated on BitTorrent and was still available
in 2010. Due to the simplicity of the Gopher protocol, setting up new
servers or adding Gopher support to browsers is often done in a
tongue-in-cheek manner, principally on April Fools' Day.
*In November 2014 Veronica indexed 144 gopher servers, reflecting a
small drop from 2012, but within these servers Veronica indexed
approximately 3 million unique selectors.
*In March 2016 Veronica indexed 135 gopher servers, within which it
indexed approximately 4 million unique selectors.
*In March 2017 Veronica indexed 133 gopher servers, within which it
indexed approximately 4.9 million unique selectors.
*In May 2018 Veronica indexed 260 gopher servers, within which it
indexed approximately 3.7 million unique selectors.
*In May 2019 Veronica indexed 320 gopher servers, within which it
indexed approximately 4.2 million unique selectors.
*In January 2020 Veronica indexed 395 gopher servers, within which it
indexed approximately 4.5 million unique selectors.
*In February 2021 Veronica indexed 361 gopher servers, within which it
indexed approximately 6 million unique selectors.
*In February 2022 Veronica indexed 325 gopher servers, within which it
indexed approximately 5 million unique selectors.
Technical details
======================================================================
The conceptualization of knowledge in "Gopher space" or a "cloud" as
specific information in a particular file, and the prominence of the
FTP, influenced the technology and the resulting functionality of
Gopher.
Gopher characteristics
========================
Gopher is designed to function and to appear much like a mountable
read-only global network file system (and software, such as
[gopher://gopher.r-36.net/1/scm/gopherfs gopherfs], is available that
can actually mount a Gopher server as a FUSE resource). At a minimum,
whatever can be done with data files on a CD-ROM, can be done on
Gopher.
A Gopher system consists of a series of hierarchical hyperlinkable
menus. The choice of menu items and titles is controlled by the
administrator of the server.
Similar to a file on a Web server, a file on a Gopher server can be
linked to as a menu item from any other Gopher server. Many servers
take advantage of this inter-server linking to provide a directory of
other servers that the user can access.
Protocol
==========
The Gopher protocol was first described in . Internet Assigned Numbers
Authority (IANA) has assigned Transmission Control Protocol (TCP) port
70 to the Gopher protocol. The protocol is simple to negotiate, making
it possible to browse without using a client.
User request
==============
First, the client establishes a TCP connection with the server on port
70, the standard gopher port. The client then sends a string followed
by a carriage return followed by a line feed (a "CR + LF" sequence).
This is the selector, which identifies the document to be retrieved.
If the item selector were an empty line, the default directory would
be selected.
Server response
=================
The server then replies with the requested item and closes the
connection. According to the protocol, before the connection closes,
the server should send a full-stop (i.e., a period character) on a
line by itself. However, not all servers conform to this part of the
protocol and the server may close a connection without returning a
final full-stop. The main type of reply from the server is a text or
binary resource. Alternatively, the resource can be a menu: a form of
structured text resource providing references to other resources.
Because of the simplicity of the Gopher protocol, tools such as netcat
make it possible to download Gopher content easily from a command
line:
$ echo jacks/jack.exe | nc gopher.example.org 70 > jack.exe
The protocol is also supported by cURL as of 7.21.2-DEV.
Search request
================
The selector string in the request can optionally be followed by a tab
character and a search string. This is used by item type 7.
Source code of a menu
=======================
Gopher menu items are defined by lines of tab-separated values in a
text file. This file is sometimes called a 'gophermap'. As the source
code to a gopher menu, a gophermap is roughly analogous to an HTML
file for a web page. Each tab-separated line (called a 'selector
line') gives the client software a description of the menu item: what
it is, what it is called, and where it leads to. The client displays
the menu items in the order that they appear in the gophermap.
The first character in a selector line indicates the 'item type',
which tells the client what kind of file or protocol the menu item
points to. This helps the client decide what to do with it. Gopher's
item types are a more basic precursor to the media type system used by
the Web and email attachments.
The item type is followed by the 'user display string' (a description
or label that represents the item in the menu); the selector (a path
or other string for the resource on the server); the 'hostname' (the
domain name or IP address of the server), and the network port.
All lines in a gopher menu are terminated by "CR + LF".
Example of a selector line in a menu source: The following selector
line generates a link to the "/home" directory at the subdomain
gopher.floodgap.com, on port 70. The item type of indicates that the
linked resource is a Gopher menu itself. The string "Floodgap Home" is
what the client will show to the user when visiting the example menu.
1Floodgap Home /home gopher.floodgap.com 70
Item type !! User display string !! Selector !! Hostname !! Port
1 Floodgap Home /home gopher.floodgap.com 70
Item types
============
In a Gopher menu's source code, a one-character code indicates what
kind of content the client should expect. This code may either be a
digit or a letter of the alphabet; letters are case-sensitive.
The technical specification for Gopher, , defines 14 item types. The
later gopher+ specification defined an additional 3 types. A
one-character code indicates what kind of content the client should
expect. Item type is an error code for exception handling. Gopher
client authors improvised item types (HTML), (informational
message), and (sound file) after the publication of RFC 1436.
Browsers like Netscape Navigator and early versions of Microsoft
Internet Explorer would prepend the item type code to the selector as
described in , so that the type of the gopher item could be determined
by the url itself. Most gopher browsers still available, use these
prefixes in their urls.
colspan="2"
| || Text file
| || Gopher submenu
| || CCSO Nameserver
| || Error code returned by a Gopher server to indicate failure
| || BinHex-encoded file (primarily for Macintosh computers)
| || DOS file
| || uuencoded file
| || Gopher full-text search
| || Telnet
| || Binary file
| || Mirror or alternate server (for load balancing or in case of
primary server downtime)
| || GIF file
| || Image file
| || Telnet 3270
colspan="2"
| || Bitmap image
| || Movie file
| || Sound file
colspan="2"
| **d** || Doc. Seen used alongside PDF and .doc files
| **h** || HTML file
| **i** || Informational message, widely used.
| **p** || image file "(especially the PNG format)"
| **r** || document RTF file ("Rich Text Format")
| **s** || Sound file (especially the WAV format)
| **P** || PDF (Portable Document Format) file
| **X** || XML (Extensible Markup Language) file
Here is an example gopher session where the user requires a gopher
menu ( on the first line):
/Reference
1CIA World Factbook /Archives/mirrors/textfiles.com/politics/CIA
gopher.quux.org 70
0Jargon 4.2.0 /Reference/Jargon 4.2.0 gopher.quux.org 70 +
1Online Libraries /Reference/Online Libraries
gopher.quux.org 70 +
1RFCs: Internet Standards /Computers/Standards and Specs/RFC
gopher.quux.org 70
1U.S. Gazetteer /Reference/U.S. Gazetteer gopher.quux.org 70
+
iThis file contains information on United States fake (NULL)
0
icities, counties, and geographical areas. It has fake (NULL)
0
ilatitude/longitude, population, land and water area, fake (NULL)
0
iand ZIP codes. fake (NULL) 0
i fake (NULL) 0
iTo search for a city, enter the city's name. To search fake
(NULL) 0
ifor a county, use the name plus County -- for instance, fake
(NULL) 0
iDallas County. fake (NULL) 0
The gopher menu sent back from the server, is a sequence of lines each
of which describes an item that can be retrieved. Most clients will
display these as hypertext links, and so allow the user to navigate
through gopherspace by following the links.
This menu includes a text resource (itemtype on the third line),
multiple links to submenus (itemtype , on the second line as well as
lines 4-6) and a non-standard information message (from line 7 on),
broken down to multiple lines by providing dummy values for selector,
host and port.
External links
================
Historically, to create a link to a Web server, "GET /" was used as a
pseudo-selector to emulate an HTTP GET request. John Goerzen created
an addition to the Gopher protocol, commonly referred to as "URL
links", that allows links to any protocol that supports URLs. For
example, to create a link to http://gopher.quux.org/, the item type is
, the display string is the title of the link, the item selector is
"URL:http://gopher.quux.org/", and the domain and port are that of the
originating Gopher server (so that clients that do not support URL
links will query the server and receive an HTML redirection page).
* [gopher://gopher.floodgap.com/1/world List of public Gopher servers]
(Gopher link)
([http://gopher.floodgap.com/gopher/gw?a=gopher%3A%2F%2Fgopher.floodgap.com%2F1%2Fworld
proxied link])
*
[https://groups.google.com/group/comp.sys.mac.announce/msg/24ad9de8dcfd6e4b
An announcement of Gopher on the Usenet 8 October 1991]
* [http://gopher.floodgap.com/overbite/relevance.html Why is Gopher
Still Relevant?] - a position statement on Gopher's survival
*
[https://arstechnica.com/tech-policy/news/2009/11/the-web-may-have-won-but-gopher-tunnels-on.ars
The Web may have won, but Gopher tunnels on] - an article published by
the technology discussion site 'Ars Technica' about the Gopher
community of enthusiasts as of 5 November 2009
*
[https://www.minnpost.com/business/2016/08/rise-and-fall-gopher-protocol
History of Gopher] - Article in MinnPost
* [gopher://gopherpedia.com/ Gopherpedia] - Gopher interface for
Wikipedia (Gopher link)
([https://gopher.floodgap.com/gopher/gw?gopher%3A%2F%2Fgopherpedia.com%2F1
proxied link], [http://gp.ratthing.com/gopherpedia.com by another
proxy])
* Mark McCahill and Farhad Anklesaria - gopher inventors - explain the
evolution of gopher: [https://www.youtube.com/watch?v=dNY9RscP-lI part
1], [https://www.youtube.com/watch?v=RObkISaq8wc part 2]
* [gopher://gopher.floodgap.com/0/gopher/tech/gopherplus.txt Proposed
Gopher+ Specification] (gopher link)
Gopher+
=========
Gopher+ is a forward compatible enhancement to the Gopher protocol.
Gopher+ works by sending metadata between the client and the server.
The enhancement was never widely adopted by Gopher servers.
The client sends a tab followed by a +. A Gopher+ server will respond
with a status line followed by the content the client requested. An
item is marked as supporting Gopher+ in the Gopher directory listing
by a tab + after the port (this is the case of some of the items in
the example above).
Other features of Gopher+ include:
* Item attributes, which can include the items
** Administrator
** Last date of modification
** Different views of the file, like PostScript or plain text, or
different languages
** Abstract, or description of the item
* Interactive queries
Gopher clients
================
These are clients, libraries, and utilities primarily designed to
access gopher resources.
Client Updated License Language Type Notes
| [https://gitlab.com/SSS8555/acid/-/blob/master/README.md ACID]
2021 ? C GUI (Windows) Supports page cache, TFTP and has G6 extension.
| [https://bombadillo.colorfield.space/ Bombadillo] 2022 GPLv3 Go
TUI (Linux, BSD, macOS) Supports Gopher, Gemini, Finger
| cURL 2024 C CLI
| [https://lists.sr.ht/~michel-slm/elpher elpher] 2022 GPLv3 Emacs
Lisp TUI/GUI Elpher: a gopher, finger, and gemini client for GNU Emacs
| [https://codeberg.org/jeang3nie/eva eva] 2022 GPLv3 Rust GUI Eva
(as in extra vehicular activity, or spacewalk) is a Gemini and Gopher
protocol browser in GTK 4.
|[http://www.jaruzel.com/gopher/gopher-client-browser-for-windows
Gopher Browser] 2019 Closed source VB.NET GUI (Windows)
| [http://forthworks.com/iOS Gopher Client] 2018 App (iOS) Supports
text reflow, bookmarks, history, etc.
| [https://gitlab.com/biotstoiq/gophercle gophercle] 2022 MIT Java
App (Android) Supports only basic functionalities like bookmarks,
session-history, downloads, etc.
| [http://gopherus.sourceforge.net/ Gopherus] 2020 BSD 2-clause C
TUI (Linux, BSD, Windows, DOS) Features bookmarks and page caching.
| [https://gophie.org/ Gophie] 2020 GPLv3 Java GUI (Windows, MacOS,
Linux)
| [https://kristall.random-projects.net/ Kristall] 2020 GPLv3 C++ GUI
(Linux) Gemini GUI client with support for Gopher, Finger, and www.
|[https://github.com/skyjake/lagrange Lagrange] 2022 BSD 2-clause C
GUI Gemini GUI client with Gopher and finger support. Switches to
gophermap/type 1 requests in parent/root navigation.
|[http://runtimeterror.com/tools/gopher/ Little Gopher Client] 2019
Pascal Linux, Mac, Windows Sidebar with a hierarchical view
| [https://github.com/jansc/ncgopher ncgopher] 2022 BSD 2-clause
Rust TUI ncgopher is a gopher and gemini client using ncurses.
| [https://github.com/afonsotrepa/PocketGopher Pocket Gopher] 2019
Unlicense Java App (Android) Supports bookmarks, history, downloads,
etc.
2022 C TUI sacc(omys) is a terminal gopher client.
| [https://www.xach.com/snarf/ snarf] 2020 GPL C CLI Simple
Non-interactive All-purpose Resource Fetcher
| w3m 2021 MIT C TUI w3m is a text-based web browser
Other clients
===============
Clients like web browsers, libraries, and utilities primarily designed
to access World Wide Web resources, but which maintain(ed) gopher
support.
* Browse, a browser for RISC OS
* Camino, versions 1.0 to 2.1.2, always uses port 70.
* Classilla, versions 9.0 to 9.3.4b1 as of March 2021, hardcoded to
port 70 from 9.0 to 9.2; whitelisted ports from 9.2.1
* Dillo+
* Dooble
* ELinks, versions 0.10.0 to 0.12pre6 as of October 2012, unmaintained
browser with gopher build option. Fork 'felinks' offers support as a
build option
* Edbrowse, a line-oriented editor and browser with an interface like
that of ed (text editor)
* Falkon, with plug-in only, requires Falkon ≥ 3.1.0 with both the KDE
Frameworks Integration extension (shipped with Falkon ≥ 3.1.0) enabled
and the (separate) kio_gopher plug-in ≥ 0.1.99 (first release for KDE
Frameworks 5) installed
* Mozilla Firefox versions 0.1 to 3.6, built-in support dropped from
Firefox 4.0 onwards; can be added back by installing one of the
extensions by the Overbite Project
* Galeon version 2.0.7
* Google Chrome, with extension only, Burrow extension
* Internet Explorer for Mac version 5.2.3, PowerPC-only
* Internet Explorer, dropped with version 6: Support removed by
MS02-047 from IE 6 SP1 can be re-enabled in the Windows Registry.
Always uses port 70. Gopher support was disabled in Internet Explorer
versions 5.x and 6 for Windows in August 2002 by a patch meant to fix
a security vulnerability in the browser's Gopher protocol handler to
reduce the attack surface which was included in IE6 SP1; however, it
can be re-enabled by editing the Windows registry. In Internet
Explorer 7, Gopher support was removed on the WinINET level.
* K-Meleon, dropped support
* Konqueror, with plug-in only, requires kio_gopher plug-in
* Line Mode Browser, since version 1.1, January 1992
* Lynx
* Mosaic, version 3.0
* NetSurf, under development, based on the cURL fetcher
* Netscape Navigator, version 9.0.0.6
* OmniWeb, since version 5.9.2 , first WebKit Browser to support
Gopher
* Opera, Opera 9.0 included a proxy capability
* Pavuk, a web mirror (recursive download) software program
* SeaMonkey, version 1.0 to 2.0.14, built-in support dropped from
version 2.1 onward; could be added back to some versions via Overbite
project, but no longer supported.
* Epiphany, until version 2.26.3, disabled with switch to WebKit
* WebPositive, a WebKit-based browser used in the Haiku operating
system
* libwww, versions 1.0c to 5.4.1 , libwww is a discontinued API for
internet applications. A modern fork is maintained in Lynx
Browsers with no Gopher native support can still access servers using
one of the available Gopher to HTTP gateways or proxy server that
converts Gopher menus into HTML; known proxies are the Floodgap Public
Gopher proxy and Gopher Proxy. Similarly, certain server packages such
as GN and PyGopherd have built-in Gopher to HTTP interfaces. Squid
Proxy software gateways any gopher:// URL to HTTP content, enabling
any browser or web agent to access gopher content easily.
For Mozilla Firefox and SeaMonkey, Overbite extensions extend Gopher
browsing and support the current versions of the browsers (Firefox
Quantum v ≥57 and equivalent versions of SeaMonkey):
* OverbiteWX redirects gopher:// URLs to a proxy;
* OverbiteNX adds native-like support;
* for Firefox up to 56.*, and equivalent versions of SeaMonkey,
OverbiteFF adds native-like support, but it is no longer maintained
OverbiteWX includes support for accessing Gopher servers not on port
70 using a whitelist and for CSO/ph queries. OverbiteFF always uses
port 70.
For Chromium and Google Chrome, Burrow is available. It redirects
gopher:// URLs to a proxy. In the past an Overbite proxy-based
extension for these browsers was available but is no longer maintained
and does not work with the current (>23) releases.
For Konqueror, Kio gopher is available.
As the bandwidth-sparing simple interface of Gopher can be a good
match for mobile phones and personal digital assistants (PDAs), the
early 2010s saw a renewed interest in native Gopher clients for
popular smartphones.
Gopher popularity was at its height at a time when there were still
many equally competing computer architectures and operating systems.
As a result, there are several Gopher clients available for Acorn RISC
OS, AmigaOS, Atari MiNT, Conversational Monitor System (CMS), DOS,
classic Mac OS, MVS, NeXT, OS/2 Warp, most Unix-like operating
systems, VMS, Windows 3.x, and Windows 9x. GopherVR was a client
designed for 3D visualization, and there is even a Gopher client in
MOO. Most such clients are hard-coded to work on Transmission Control
Protocol (TCP) port 70.
Server software
======================================================================
Because the protocol is trivial to implement in a basic fashion, there
are many server packages still available, and some are still
maintained.
Server Developed by Latest version Release date License Written in
Notes
[http://aftershock.sourceforge.net/ Aftershock] Rob Linwood 1.0.1
MIT Java
[https://metacpan.org/pod/Apache::GopherHandler
Apache::GopherHandler] Timm Murray 0.1 GPLv2 or any later version
Perl Apache 2 plugin to run Gopher-Server.
[https://github.com/crcx/atua Atua] Charles Childers 2017.4 ISC
Forth
[gopher://gopher.floodgap.com/1/buck/ Bucktooth] (gopher link)
([http://gopher.floodgap.com/gopher/gw?a=gopher%3A%2F%2Fgopher.floodgap.com%2F1%2Fbuck
proxied link]) Cameron Kaiser 0.2.10 Floodgap Free Software License
Perl
[https://github.com/michael-lazar/flask-gopher Flask-Gopher] Michael
Lazar 2.2.1 GPLv3 Python
[https://github.com/heddwch/geomyid geomyid] Quinn Evans 0.0.1 BSD
2-clause Common Lisp
[gopher://gopher.r-36.net/1/scm/geomyidae geomyidae] (gopher link)
([http://gopher.floodgap.com/gopher/gw?a=gopher%3A%2F%2Fgopher.r-36.net%2F1%2Fscm%2Fgeomyidae
proxied link]) Christoph Lohmann 0.96 MIT C |REST dynamic scripting,
gopher TLS support, compatibility layer for other gophermaps
[http://gofish.sourceforge.net/ GoFish] Sean MacLennan 1.2 GPLv2 C
[https://git.mills.io/prologic/go-gopher go-gopher] James Mills MIT
Go
[https://metacpan.org/release/Gopher-Server Gopher-Server] Timm
Murray 0.1.1 GPLv2 Perl
[http://gophernicus.org/ Gophernicus] Kim Holviala and others 3.1.1
BSD 2-clause C
[http://gophrier.tuxfamily.org/ gophrier] Guillaume Duhamel 0.2.3
GPLv2 C
[https://github.com/arcfide/goscher Goscher] Aaron W. Hsu 8.0 ISC
Scheme
[https://port70.net/?1mgod mgod] Mate Nagy 1.1 GPLv3 C
[http://motsognir.sourceforge.net/ Motsognir] Mateusz Viste 1.0.13
MIT C extensible through custom gophermaps, CGI and PHP scripts
[https://github.com/dotcomboom/Pituophis Pituophis] dotcomboom 1.1
BSD 2-clause Python Python-based Gopher library with both server and
client support
[https://github.com/michael-lazar/pygopherd PyGopherd] Michael Lazar
3.0.1 GPLv2 Python Also supports HTTP, WAP, and Gopher+
[https://redis.io/docs/reference/gopher/ Redis] Salvatore Sanfilippo
6.2.5 3-clause BSD C Support removed in version 7
[https://gitlab.com/SSS8555/save_gopher_server save_gopher_server]
SSS8555 0.777 Perl with G6 extension and TFTP
[https://github.com/sternenseemann/spacecookie Spacecookie] Lukas
Epple 1.0.0.0 GPLv3 Haskell
[https://gitlab.com/leveck/xylophar Xylophar] Nathaniel Leveck 0.0.1
GPLv3 FreeBASIC
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL: http://creativecommons.org/licenses/by-sa/3.0/
Original Article: http://en.wikipedia.org/wiki/Gopher_(protocol)