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Versions: 00 01 02 03                                                   
Network Working Group                                         T. Matavka
Internet-Draft
Updates: 1436, 4266 (if approved)                               W. Faust
Intended status: Standards Track                            June 8, 2015
Expires: December 10, 2015


               Gopher-II: The Next Generation Gopher WWIS
                       draft-matavka-gopher-ii-02

Abstract

   The Gopher protocol is over twenty years old.  Changing practices and
   unofficial extensions have caused Gopher as currently used to differ,
   but remain largely compatible with, the standard established in its
   official governing document, *The Internet Gopher Protocol (a
   distributed document search and retrieval protocol)*, known as *RFC
   1436*.  Therefore, this document attempts to establish a contemporary
   specification of the Gopher communications protocol, departing as
   little as possible from current practice.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 10, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Changes from RFC 1436 and 4266  . . . . . . . . . . . . .   3
   2.  Basic Gopher Transactions . . . . . . . . . . . . . . . . . .   4
     2.1.  Menu Transaction  . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Index Transaction . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Simple Text Transaction . . . . . . . . . . . . . . . . .   5
     2.4.  Binary Transaction  . . . . . . . . . . . . . . . . . . .   5
     2.5.  Details . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Line Terminators  . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Selector Formats  . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Type Codes  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  GopherIIbis: Metadata in Gopherspace  . . . . . . . . . .   8
   5.  Gopher Menus  . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Note on the terminating full stop . . . . . . . . . . . .  10
   6.  Requesting Data . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Data Transfer . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  Requesting and Receiving Metadata . . . . . . . . . . . . . .  12
     8.1.  The `INFO` Record . . . . . . . . . . . . . . . . . . . .  13
     8.2.  The `ADMIN` Record  . . . . . . . . . . . . . . . . . . .  13
     8.3.  The `VIEWS` Record  . . . . . . . . . . . . . . . . . . .  14
     8.4.  The `ABSTRACT` Record . . . . . . . . . . . . . . . . . .  15
   9.  Errors  . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Error Codes . . . . . . . . . . . . . . . . . . . . . . .  16
   10. Titles in Gopher  . . . . . . . . . . . . . . . . . . . . . .  17
   11. Linking to Web Addresses  . . . . . . . . . . . . . . . . . .  18
   12. Algorithm to use with selectors . . . . . . . . . . . . . . .  20
   13. Representation of Gopher Addresses  . . . . . . . . . . . . .  21
   14. Gopher Policy Files . . . . . . . . . . . . . . . . . . . . .  22
     14.1.  Capability Policy  . . . . . . . . . . . . . . . . . . .  22
     14.2.  Robot Access Restrictions Policy . . . . . . . . . . . .  25
     14.3.  Administrator Contact File . . . . . . . . . . . . . . .  28
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
   16. Security Considerations . . . . . . . . . . . . . . . . . . .  29
   17. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  30
   18. References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     18.1.  Normative References . . . . . . . . . . . . . . . . . .  30
     18.2.  Informative References . . . . . . . . . . . . . . . . .  31
   Appendix A.  Summary of Changes from RFC 1436 . . . . . . . . . .  31
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  32
     B.1.  Changes from -00 to -01 of this specification . . . . . .  32



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     B.2.  Changes from -01 to -02 of this specification . . . . . .  32
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  32

1.  Introduction

   The over-riding aim of this document is to author a contemporary
   specification of the Gopher world-wide information system, without
   falling short of reflecting actual practice and without breaking
   compliance with RFC 1436 [RFC1436].  This document shall attempt to
   describe, and, where necessary, update current practice as regards
   the means of handling errors, line and file terminators, policy
   files, TITLE selectors, the URL: re-direction scheme, and new
   selector types not compliant with RFC 1436.  This document is not to
   be construed as a replacement for RFC 1436; it merely complements it.

   Gopher is a lightweight, client/server-oriented query/answer
   protocol, functioning as a world-wide information system (WWIS) and
   facilitating access to remote servers of any description.  The
   protocol and software permit users of a wide variety of desktop
   systems to browse, search, and retrieve documents residing on
   multiple distributed server machines.  Gopher is unique among world-
   wide information systems in that it encourages data to be sent in
   textual form and that it imposes a strict hierarchy on content,
   making it a protocol that is fast to transmit, receive, and search.
   This, in turn, makes it useful in high-latency, low-bandwidth
   communications, such as mobile links.  In fact, Gopher provides the
   ideal method for transmitting information from and to mobile devices.

1.1.  Terminology

   NOTE: The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
   this document are to be interpreted as described in RFC 2119
   [RFC2119].  Furthermore, backticks (`) around a string mean that it
   is to be interpreted literally.

1.2.  Changes from RFC 1436 and 4266

   GopherII remains broadly compatible with the original Gopher; a
   client compatible with the original implementation of Gopher will be
   able to browse GopherII servers with a minimum of problems.  The only
   difference in strict-compatibility terms arises in the new selector
   types (including, but not limited to, one distinguishing "plain text"
   from "ASCII markup document").  That said, although these new
   selectors are not officially standardised in RFC 1436, most existing
   Gopher clients will ask for user input when attempting to process an
   unfamiliar selector, and these selectors have been in de facto use




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   for some time, such that current Gopher clients will be compatible
   with them already.

   GopherII modifies the original standard in eight ways.  Aside from
   the aforementioned new selector types, GopherII introduces the
   concept of the so-called policy file.  Policy files are configuration
   files sent from the server to the client in ASCII form with a defined
   syntax.  Three policy files are defined in this document: the
   capability policy, which defines architectural details of the server
   (including information about the file system); the administrator
   contact file, which defines the geographical location of the server
   as well as the entity responsible for its maintenance, and the robot
   access restrictions policy, which defines etiquette to be followed by
   Gopher search engines.  The word 'etiquette' is here used because,
   like human codes of behaviour at mealtime, it is non-binding.

   Policy files account for three of the substantive changes from
   original Gopher.  GopherII also adds HTTP-style error codes, a
   mechanism for titling the Gopher client window or tab, and
   standardises a backward-compatible method for linking to HTTP
   addresses.  The final change is that GopherII adds support for the
   metadata system known as Gopher+ (GopherIIbis in this document),
   although this part of the GopherII specification is entirely
   optional.

2.  Basic Gopher Transactions

   There are four broad forms of basic transactions in Gopher:

   o  Menu Transaction;

   o  Index Transaction;

   o  Simple Text Transaction; and

   o  Binary Transaction.

   The precise composition of these transactions is elucidated below.

2.1.  Menu Transaction

   o  Client : [Open Connexion]

   o  Client : Send [selector<CR><LF>]

   o  Server : Send <Menu>

   o  Server : Send .



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   o  Server : [Close Connexion]

2.2.  Index Transaction

   o  Client : [Open Connexion]

   o  Client : Send [selector<TAB>query parameters<CR><LF>]

   o  Server : Send [<Menu>]

   o  Server : Send .

   o  Server : [Close Connexion]

2.3.  Simple Text Transaction

   o  Client : [Open Connexion]

   o  Client : Send [selector<CR><LF>]

   o  Server : Send [<Simple Text>]

   o  Server : Send .

   o  Server : [Close Connexion]

2.4.  Binary Transaction

   o  Client : [Open Connexion]

   o  Client : Send [selector<CR><LF>]

   o  Server : Send [<Raw Binary Data>]

   o  Server : DO NOT send .

   o  Server : [Close Connexion]

2.5.  Details

   The fourth step of each transaction, with the exception of the binary
   type, is OPTIONAL.  Servers MAY send a full-stop character after
   sending a menu, index, or text; if they do, clients MUST accept it.
   Further information may be found in the appropriate sub-section.

   Gopher servers are normally found on TCP port 70.  Clients MUST
   assume this port if no other port is specified.  When a client opens
   a connection to a server, the server MUST accept the connection but



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   say nothing, waiting for a CR/LF-terminated selector string from the
   client.  The client MAY then send the selector string followed by CR/
   LF (or nothing to retrieve the root menu from the server, which MUST
   always be type 1).  The server MUST then send the requested content
   and close the connection.

3.  Line Terminators

   ASCII, the international standard that governs the interchange of
   plain-text information between computer systems, is nothing more or
   less than a table mapping each character (letter, number, space, or
   symbol) to a numerical code, which is then converted to binary and
   written to disc.  Its necessity was seen long before the advent of
   the electronic monitor, so some of its more unique quirks must be
   understood in view of the time period of which it was a product.
   Historically, input and output was through a specially-adapted
   typewriter, and the ASCII convention reflects this in the codes it
   uses to terminate lines of text.

   In ASCII, there are two codes, both having physical equivalents in
   the real world, that signal the end of the line: the Carriage Return
   (abbreviated C/R, CR, or c/r) and the Line Feed (abbreviated L/F, LF,
   or l/f).  Originally, the term *carriage return* was used for a
   command that caused the assembly holding the paper (the carriage) to
   return to the right so the machine was ready to type again on the
   left side of the paper (assuming a left-to-right language).  On the
   other hand, the *line feed* moved the paper upwards, allowing the
   carriage to type on the following line.

   Different operating systems traditionally signal the end of a line in
   different ways.  UNIX and its descendants (including Mac OS X), the
   operating systems most likely to run on a server, use the line feed
   alone.  CP/M, DOS, and Microsoft Windows use the sequence of carriage
   return and line feed (CR/LF).  Obsolete versions of Mac OS (up to,
   and including, System 9) use the carriage return alone.

   All programmes using Gopher MUST always use the Microsoft standard of
   CR/LF, irrespective of the operating system they run on.  Both
   internal Gopher commands and policy files MUST comply with this
   standard.  Other text files SHOULD use standard Gopher format, but
   this is not strictly required as a matter of technical form; the
   client MUST be capable of converting to and from all variants of line
   terminators.  The recommendation stands for the benefit of non-
   compliant clients only.







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4.  Selector Formats

4.1.  Type Codes


 The following selectors are defined by RFC 1436:

     Type    Treat As    Meaning
     0       TEXT        Plain text file
     1       MENU        Menu
     2       EXTERNAL    CCSO flat database (formerly used as telephone
                         directories); other databases
     3       ERROR       Error message
     4       TEXT        Macintosh BinHex file
     5       BINARY      Binary archive (zip; rar; 7-Zip; gzip; tar)
     6       TEXT        UUEncoded archive
     7       INDEX       Query a search engine or CGI script
     8       EXTERNAL    Telnet to: VT100 series server
     9       BINARY      Binary file (see also 5)
     +       -           Redundant server
     T       EXTERNAL    Telnet to: tn3270 series server
     g       BINARY      GIF format graphics file (TODO: Why not use I?)
     I       BINARY      Any image file.

   The `+` selector indicates a mirror of the previous item in the menu,
   and MUST behave as though it had the same type as that entry.  For
   example:

   5Download software /software.zip gopher.example.com 70
   +example.net mirror mirror.example.net /example.com/software.zip 70
   +Another mirror mirror2.example.com /software.zip 70

   Additionally, the following selectors have been in common use and are
   made official here.  If a client does not have the capability to
   display a particular item type, it SHOULD treat it as a more generic
   item type, passing it off to the operating system (itemtype p
   "implies" itemtype 0, etc.).














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       Type    Treat As    Meaning
       c       BINARY      Calendar file (Kim Holviala)
       d       BINARY      Word-processing document (MS
                           Word; OpenOffice.org;
                           WordPerfect); PDF document
       h       TEXT        HTML document
       i       -           Informational text (not
                           selectable)

       p       TEXT        Page layout or markup document
                           (TeX; LaTeX; PostScript; Rich
                           Text Format)---these documents are
                           all plain text, but contain ASCII
                           tags" that make the document
                           prettier when sent through a
                           special program.
       m       BINARY      Electronic mail repository (also
                           known as MBOX) (Kim Holviala)
       s       BINARY      Audio recordings (files that
                           consist of audible, but no
                           visible, data) (Wesley Teal)
       x       TEXT        eXtensible Markup Language
                           document (Wesley Teal)
       ;       BINARY      Video files (files that consist
                           of both audible and visible
                           data) (Wesley Teal)

   Filetypes `4`, `6`, `h`, `p`, and `x` SHOULD send as text (itemtype
   0).  This way, the text appears directly on the user's terminal
   without being downloaded (unless the appropriate command is given to
   the client, i.e.  `CTRL/S`).  It is vital to note that text
   information can be sent via binary (with the minor inconvenience
   noted above), as binary files contain a greater range of information
   than ASCII.  However, binary files, if sent via text, will be
   irreparably ruined, as this effectively passes raw eight-bit data
   through an ASCII filter.  In the case of confusion, the owner/
   operator of the server should simply mark the file as binary to
   ensure that it transfers safely.

4.2.  GopherIIbis: Metadata in Gopherspace

   It is sometimes useful to transmit data about GopherII selectors.
   This is known as "metadata": the *meta* construction is derived from
   the Greek for "beyond", and refers to concepts which are abstractions
   from other concepts intended to complete or add to the latter.  For
   instance, in psychology, metamemory refers to an individual's ability
   to remember that he has remembered something.  In plain English,
   metadata refers to data about data.



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   GopherIIbis is an OPTIONAL, but recommended, addition to the basic
   GopherII specification.  That said, it is optional only in the sense
   that a GopherII client MAY EITHER display the relevant information in
   accordance with the specification, or ELSE ignore it entirely.  To be
   conformant with GopherII, Gopher clients MUST be capable of handling
   GopherIIbis metadata.  A GopherII client that displays GopherIIbis
   metadata may be referred to as being compliant with GopherIIbis.

   The name of the GopherIIbis extension is pronounced "gopher-two-biss"
   or "gopher-two-beess".  In typeset text, the French word "bis" should
   be *italicised* so as to set it off visually.  The name of the
   GopherIIbis extension reflects that it is merely an addition, or an
   iteration, of the GopherII protocol.

5.  Gopher Menus

   Menu (type 1) content has the following format:

   T<itemtext>^I<selector>^I<host>^I<port>

   Where:

   o  `^I` is the ASCII character corresponding to the `Tab` key

   o  `T` is the type code, which MUST be run together with the item
      text

   o  <selector> is the selector string to send to the specified server

   o  <host> is the server to send the selector to

   o  <port> is the port on the server to connect to

   If the server understands how to send and receive GopherIIbis
   metadata, it MUST indicate this fact by adding a fourth tab character
   (^I) and a plus sign after the port number.  For example:

   T<itemtext>^I<selector>^I<host>^I<port>^I+

   If the client does not understand GopherIIbis metadata, it MUST
   ignore the trailing ^I+.

   Note on `i` item type: For the `i` item type, Selector, Server, and
   Port are mostly ignored, but MUST be there anyway.  In that case, the
   host SHOULD be set to placeholder value `example.com`, and the port
   SHOULD be set to placeholder value `0` (zero).  One exception to
   their being ignored is TITLE entries.  These have TITLE as the




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   selector value; host and port SHOULD again be set to aforementioned
   placeholder values.

5.1.  Note on the terminating full stop

   Per RFC 1436, a terminating full stop (.) character followed by CR/LF
   should be sent on a line by itself after the end of the content, with
   exceptions for binary data.  This terminating full stop has caused no
   end of trouble ever since.  Many, if not most, modern Gopher servers
   omit this terminating full stop.  Therefore, the practice suggested
   in RFC 1436 is DEPRECATED and the following practice is RECOMMENDED.

   o  Servers MAY send the full stop; clients MUST accept it

   o  Servers SHOULD send the full stop after menus and may OPTIONALLY
      send it after other files

   o  Clients SHOULD display the full stop at the end of menus, if sent,
      to notify the user that this is the end of the menu

   o  Clients SHOULD NOT include the full stop in other output, in case
      that output has some significance which the full stop may disrupt.

   o  Clients SHOULD NOT consider a full stop significant, unless it
      occurs immediately before the connection is terminated.

6.  Requesting Data

   A standard GopherII client requests data from the server by
   transmitting the selector string, a carriage return, and a line feed.
   For instance, to retrieve the file `services.txt`, the client sends

      services.txt[CR][LF]

   GopherIIbis handles things in a slightly more complicated way.  In
   addition to a selector string, a GopherIIbis-compliant request
   contains a *format* string, a data flag indicating the presence or
   absence of a data block, and an OPTIONAL data block.

   The reason for the inclusion of the format string is because
   GopherIIbis allows one selector to point to multiple versions of the
   same file, in multiple languages.  For instance, the same file in
   Portable Document Format, PostScript format, Rich Text Format, and
   plain text may be available, and each of these may be available in
   British English, American English, Canadian French, and Continental
   French.  The format string, therefore, is the desired MIME type of
   whichever format is being requested, followed by the ISO country and
   language codes in the following format:



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      selector^Imime/type la_CO^I1[CR][LF]datadatadatadata

   The number 1 above is the file flag.  It can be either 1 or 0.  If it
   is 1, it means that the client is not only requesting data, but also
   *sending* it.  This is useful for example when querying a relational
   database on a Gopher server (this usage is now rare).  An example
   would be:

      services.txt^Itext/plain fr_CA^I0[CR][LF]

7.  Data Transfer

   When a file is requested by a Gopher client, a Gopher server
   incompatible with GopherIIbis simply sends the requested data as soon
   as it gets the request from the client.  GopherIIbis servers, on the
   other hand, have three options when given a GopherIIbis-compliant
   request (i.e.  one that ends in ^I+).

   If the size of the file in bytes is known, the server SHOULD transmit
   a plus sign, the size, and the combination of carriage return and
   line feed, then the file.  For example, if the size of file
   `report.tex` is known to be 64096 bytes, the server SHOULD transmit:

      +64096[CR][LF]\documentclass{article}[CR][LF]\begin{document}...

   If the size of the file is not known, there are two ways to proceed.
   One of them is to send the character string `+-1` prior to beginning
   transmission of the data proper, and end the transmission with a full
   stop (.) on a line by itself, followed by carriage return and line
   feed.  For example:

      +-1[CR][LF]data data[CR][LF]data data data data[CR][LF].[CR][LF]

   It is RECOMMENDED that most textual data of unknown length be
   transmitted this way.  The exception is when there is a possibility
   of the full stop appearing on a line by itself; this, of course,
   would terminate the connexion.  There is no choice when sending non-
   textual (binary) data: it MUST NOT be terminated with a full stop.

   In either of the two cases above, the string to send is `+-2`.  This
   instructs the client that the data will be terminated when the
   connexion is closed, and furthermore, that the length of the data is
   unknown.  For example:

      +-2[CR][LF]binarydata <connexion severed by host>






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8.  Requesting and Receiving Metadata

   A GopherIIbis client may request the metadata for a specific selector
   by sending a string in the following form:

      <selector>^I![CR][LF]

   The trailing tab and exclamation mark is what distinguishes a request
   for data from a request for metadata.  The metadata returned is of
   the following form:

   +INFO: 0lpryce.txt^IRest in peace, Lane Pryce^Igopher.scdp.com^I70+

   +ADMIN:
   Admin: Roger Sterling <roger@scdp.com>
   Mod-Date: Fri Feb 13 08:22:11 2015 <20130213082211>

   +VIEWS:
   text/plain: <10k>
   application/postscript: <100k>
   application/latex: <50k>
   application/pdf: <120k>

   +ABSTRACT:

   Yesterday, our beloved partner Lane Gordon Pryce died of suicide in
   his Manhattan home.  He was 55.

   In general, data intended to be read by the computer will be enclosed
   in angle brackets (`<` and `>`).  A graphical client may, for
   example, provide a GUI menu of all possible document views with
   graphical icons of the file type and tool-tips of the file size.

   These are far from the only available metadata records; only the
   `INFO` record is mandatory, and it MUST be transmitted first of all.
   The `ADMIN` record is RECOMMENDED, and if it is included, it must be
   transmitted *directly* after the `INFO` record.

   It is also possible to retrieve only a *specific* record or range of
   records.  For example, to retrieve only the views and the abstract, a
   client may send:

   <selector>^I!+INFO+ADMIN[CR][LF]

   Finally, it is possible to retrieve metadata for an *entire
   directory*.  Of course, this is relatively bandwidth-intensive (for a
   56k link) but a modern Ethernet connexion should have no problem with
   it.  The reason for the requirement of an `INFO` record for every



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   selector should now be abundantly clear: the `INFO` record serves to
   separate metadata for one file from metadata for another.  For
   example:

   <selector>^I&[CR][LF]

   The only difference between a request for a *single* file's metadata
   and a request for that of a whole directory is that a single-file
   request uses an exclamation mark, whereas a whole-directory request
   uses an ampersand ("and sign", &).

   It is even possible to request a specific record from every selector
   in the directory, by appending the requested fields to the command
   string as above.

8.1.  The `INFO` Record

   The `INFO` record is MANDATORY in every metadata listing.  It
   contains the same data as the Gopher selector, with a plus sign at
   the end, per GopherIIbis style.  It MUST always be present, and it
   MUST always be the first metadata record present.  The `INFO` record
   serves to separate metadata listings when more are sent at the same
   time.

8.2.  The `ADMIN` Record

   To promote accountability, the `ADMIN` record is also MANDATORY in
   every metadata listing.  It MUST contain fields for `Admin` (the name
   and contact information for the administrator of the file) and `Mod-
   Date` (the date of last modification) as seen in the example below:

   +ADMIN:
   Admin: Roger Sterling <roger@scdp.com>
   Mod-Date: 01 January 2015 <YYYYMMDDhhmmss>

   The time of last modification MUST be in 24-hour format.

   If the metadata listing is for the results of a database search, such
   as Veronica, it SHOULD also include fields for `Score` (a whole-
   number ranking of the relevance of the result to the search query)
   and for `Score-Range` (the lowest and highest possible relevance
   scores), as per the following example:

   +ADMIN:
   Admin: Margaret Olson <m.olson@scdp.com>
   Mod-Date: 13 February 2015 <YYYYMMDDhhmmss>
   Score: 100
   Score-Range: 0 150



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   The first number in the `Score-Range` field is the *lower bound*, and
   the second number is the *upper bound*.

   Several other fields are optional.  `Site` is the name of the
   Gopherhole, `Org` is the name of the business or individual who owns
   the Gopherhole, `Loc` is the owner's location (city, district, and
   country), `Geog` is the owner's geographic co-ordinates, and `TZ` is
   the time zone in the format GMT+[01..11].  For example:

   +ADMIN:
   ...
   Site: S|C|D|P Main Site
   Org: Sterling|Cooper|Draper|Pryce Inc.
   Loc: New York, NY, USA
   Geog: 40N 173W
   TZ: GMT-05

   The `Author` may also be given, as may be the `Creation-Date` and
   `Expiration-Date`, in the same format as the `Mod-Date`.

8.3.  The `VIEWS` Record

   Although the main selector might be for only one format of a file
   (such as Rich Text Format), the same file may be available in many
   other formats, such as Plain Text for older systems, LaTeX for
   typesetters, PDF for displaying on screen, PostScript for printing on
   a graphical printer, and many more.

   The `VIEWS` record in GopherIIbis allows for serving multiple
   variants of the same file, using what are known as MIME file
   descriptors, Content-Types, or Internet media types.  The `VIEWS`
   field also allows for viewing the same file in multiple languages and
   even in multiple dialects of the same language---in this case, the
   relevant abbreviations are known as ISO-639 language codes and
   ISO-3166 country codes.  These are generally at least somewhat
   intuitive (`CA` for Canada, `GB` for Great Britain, `en` for
   English), but a full list may be found on the ISO Web site.

   This is an example of a `VIEWS` record allowing for the selection of
   a plain text, Rich Text, and PDF of the same file in American
   English, Peninsular Portuguese, and Brazilian Portuguese:

   +VIEWS
   text/plain en_US: <32K>
   text/plain pt_PT: <34K>
   text/plain pt_BR: <34K>
   text/rtf en_US: <55K>
   text/rtf pt_PT: <60K>



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   text/rtf pt_BR: <66K>
   application/pdf en_US: <120K>
   application/pdf pt_PT: <132K>
   application/pdf pt_BR: <133K>

   The `VIEWS` record SHOULD be ranked according to the administrator's
   idea of which view is preferred.  On an American site catering to
   English speakers, the `en_US` files should be listed first of all.
   Likewise, on a site of any language catering to scientists, LaTeX
   source should always come first of all.

8.4.  The `ABSTRACT` Record

   It is RECOMMENDED that every selector on a GopherIIbis-compliant
   server have an `ABSTRACT` record.  The `ABSTRACT` record contains a
   *brief* description of the item (no more than a paragraph long) to
   assist the reader in determining its purpose.  Similarly, it is also
   RECOMMENDED that the root directory of every Gopher server (that is,
   what one gets when one requests metadata for the server itself with
   no selector) contain an `ABSTRACT` record with the name, postal
   address, eMail address, and telephone number of the person
   responsible for the site.  For example:

   +ABSTRACT
   The life and times of Professor Albert Einstein, Swiss patents clerk
   and discoverer of four great scientific theories in one miraculous
   year.

9.  Errors

   Although undesirable in communication, errors do occur in Gopher, and
   their handling is crucial for a user-friendly, and standards-
   compliant, Gopher experience.

   When an error is encountered, the server MUST return a menu whose
   first item bears itemtype `3`.  All other ways of signalling an
   error, such as redirecting to a Gopher error menu, an image, or
   (worst of all) an HTML page, are PROHIBITED.

   The selector string for itemtype `3` is the text of the error.  It is
   the responsibility of the server application to have understandable
   and accurate strings for error handling.  As they are well-understood
   and common, HTTP-style error codes are acceptable and RECOMMENDED;
   however, they SHOULD also be followed by a clear, legible description
   of the error in both English and the local language.

   Errors are handled in GopherIIbis in a slightly different fashion.
   When an error occurs in response to a GopherIIbis-compliant query,



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   the server sends two minus signs, followed by an error code, a
   description of the error, and a full stop.  The error code SHOULD be
   in the three-digit style elucidated in the next sub-subsection, but
   the numbers 1, 2, and 3 MUST also be understood and handled
   correctly, also as defined in "Error Codes".  An example of a
   GopherIIbis error follows:

   --404[CR][LF]The file requested could not be found.[CR][LF].[CR][LF]

   The decision of whether to send a GopherII error string or a
   GopherIIbis error string is governed by the type of query received.
   If the query was compliant with GopherIIbis, a GopherIIbis error MUST
   be sent.  In all other cases, a GopherII error MUST be sent.

9.1.  Error Codes

   This is a listing of numeric error codes used in Gopher; due to
   Gopher's simplicity, it lacks most of the errors possible in HTTP.
   Codes beginning with 4 can generally be traced to the client; codes
   beginning with 5 are usually due to the server.

   400 Bad Request  The request could not be understood by the server
      due to malformed syntax.

   401 Unauthorised  The request requires authentication.  For example,
      the received query value (as password) does not match the expected
      value.

   403 Forbidden  The request was received, but not filled.

   404 Not Found  The server could not find anything matching the
      requested URL.  If the condition is known to be permanent, use
      error code 410 (Gone).

   408 Request Time-out  The client did not produce a request within the
      time that the server was prepared to wait.

   410 Gone  The requested resource is no longer available at the server
      and no forwarding address is known.  This condition is expected to
      be considered permanent.  If this is unknown, use error code 404
      (Not Found).

   500 Internal Server Error  The server encountered an unexpected
      condition which prevented it from fulfilling the request.

   501 Not Implemented  The server does not support the functionality
      required to fulfil the request.




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   503 Service Unavailable  The server is currently unable to handle the
      request due to temporary overload/maintenance.

   An earlier version of the GopherIIbis extension, known as Gopher+,
   used error codes `1`, `2`, and `3`.  Error code `1` signifies an
   unavailable item (similar to the 400-series errors), error code `2`
   signifies an unavailable server (similar to the 500-series errors),
   and error code `3` signifies an item that has moved.  Provision was
   made to create new error codes.  This is now DEPRECATED; the *ad hoc*
   creation of new errors does not accord with the ethos of a
   standardised Internet protocol.

10.  Titles in Gopher

   No mention of menus with titles exists per RFC 1436.  When one simply
   browses about Gopherspace, this does not matter; for bookmarking and
   Gopher crawlers, such as Veronica-2, however, this presents a large
   problem.

   A Gopher TITLE resource has the following format:

   i<titletext>^ITITLE^Iexample.com^I0

   It is identical to a standard informational resource (itemtype `i`);
   the selector string, however, is set to the specific value, `TITLE`.

   The composition of the above format is as follows:

   o  `^I` is the ASCII character corresponding to a press of the `Tab`
      key

   o  The type code MUST be `i` (information)

   o  The selector string MUST be `TITLE`

   o  There is no server to connect to; the dummy text used in place of
      the server SHOULD be `example.com`

   o  There is no port to connect to; the placeholder number SHOULD
      therefore be `0` (zero).

   A Gopher client that conforms to the above `TITLE` specification
   SHALL render it in one of two ways, depending on the placement of the
   resource.  If the `TITLE` is the *first* resource in the document, it
   SHALL be considered its principal `TITLE` and used *wherever a
   principal title is needed* (window headings, bookmarks, etc.);
   furthermore, it SHOULD be rendered in a different size, font, and/or
   colour to the remainder of the document.  In *all other* cases, it



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   SHALL be considered a subordinate `TITLE` and SHOULD be rendered in a
   different size, font, and/or colour to the remainder of the document,
   but smaller and/or with less emphasis than the main title.

   If a non-compliant Gopher client receives a `TITLE` resource as per
   above, it will render it as plain informational text.  As the main
   `TITLE` must be on the first line of a menu, it will appear visually
   similar to a title in any case, although not rendered as such.

11.  Linking to Web Addresses

   It is now possible, and standard, to link to documents, preferably in
   HTML, on the World Wide Web, Gopher's younger, more widespread
   cousin, from Gopher itself, using a two-part system: a `URL:`
   selector on the Gopher (local) end, and a *redirect page* (following
   rules as set out below) on the HTTP (remote) end.  There are no
   compliance requirements for Gopher servers, with one exception:
   servers MUST follow the bulleted list located immediately after the
   example redirect page.

   A Gopher client SHALL, when it sees a selector with a path starting
   with `URL:`, interpret the path as a URL.  It SHALL ignore the host
   and port components of the Gopher selector, using those components
   from the URL instead, if applicable.

   `URL:` selectors SHOULD NOT be used if it is possible to link to the
   required content and protocol by any other means.  In particular, the
   following protocols SHALL NOT be used with the URL: selector.

   o  gopher

   o  telnet (VT100-compatible)

   o  tn3270

   Authors SHOULD NOT link to any document not of HTML type unless
   absolutely necessary; linking to non-HTML documents will break
   compatibility with non-compliant Gopher browsers.

   A Gopher `URL:` selector MUST take the following format:

   h<itemtext>^IURL:<address>^I<localhost>^I<localport>

   URL:` selectors are, for the most part, identical to standard HTML
   selectors, but composed of particular data:






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   o  The item type corresponds to the type of document on the remote
      end.  Most typically, this is a Web page authored in HTML;
      therefore, the item type is most commonly `h`.

   o  <itemtext> is the text of the link; this can be almost anything.

   o  <address> is the full URL, preceded by the string `URL:`.  For
      example, this could be `URL:http://www.example.com`

   o  <localhost> is the server that the link *originated* from; this
      MUST be ignored by a compliant client, but MUST also be sent by a
      compliant server

   o  <localport> is the port that the link *originated* from; this MUST
      be ignored by a compliant client, but MUST also be sent by a
      compliant server

   It is possible for a non-compliant Gopher client to follow a link to
   an HTML page, as long as the server is compliant, by the following
   means: when the client receives a command to follow a `URL:`
   selector, it will contact the server that provided the menu, as the
   originating host and port are *mandatory* per this specification.

   When a Gopher server receives a request from a client beginning with
   the string `URL:`, it SHALL write out an HTML document that redirects
   the browser to the appropriate place.  A conforming example of such a
   document is as follows:

   <HTML>
   <HEAD>
   <META HTTP-EQUIV="refresh" content="2;URL=http://www.example.com/">
   </HEAD>
   <BODY>

   You are following an external link to a Web site.  You will be
   automatically taken to the site shortly.  If you do not get sent
   there, please click <A HREF="http://www.example.com/">here</A> to go
   to the web site.
   <P>
   The URL linked is:http://www.example.com/">
   <P>
   <A HREF="http://www.example.com/">http://www.example.com/</A>
   <P>
   Thanks for using Gopher!
   </BODY>
   </HTML>





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   This document may be any desired by the server authors, but MUST
   adhere to the following requirements.

   o  It SHALL provide a refresh of a duration of 10 seconds or less

   o  It SHALL NOT use `IMG` tags, frames, or have any reference
      whatsoever to content outside that particular file, with the sole
      exception of the link to the real destination.

   o  It SHALL NOT use JavaScript.

   o  It SHALL adhere to the W3C HTML 4.0 standard.

   When a non-compliant Gopher client finds a reference to a HTML file
   (type `h`), it will open up the file via Gopher, receiving the
   redirect document using a Web browser.  The Web browser will then be
   redirected to the actual link destination.

   Compliant Gopher clients will simply render the target directly.

12.  Algorithm to use with selectors

   Here is a description for a hypothetical algorithm for parsing item
   types, splitting them into levels of interaction.



























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      PROTOCOL
      --------
      Type              Description    What to do
      0                 Brief text     Render directly line by line.
      1                 Menu           Request and analyse menu.  If it
                                       contains '3' error node, print
                                       error.
                                       Else, render menu in new window.
      7                 Index/Search
                        Server

      DATA NODES
      ----------
      Type              Description    What to do
      4, 9, g, I, c,    Binary file    Request and analyse file.  If it
      d, m, s, ;                       contains '3' error node, print
                                       error.  Else, does plug-in exist?
                                       If yes, display.  If no, save to
                                       disc.
      6, p, x           Text file      Request and analyse file.  If it
                                       contains '3' error node, print
                                       error.  Else, print on screen.
      h, 2, 8, T        Link           Treat as URL.
      5                 Archive File   Request and analyse file.  If it
                                       contains '3' error node, print
                                       error.  Else, does plug-in exist?
                                       If yes, display.  If no, save to
                                       disc.


   For instance, if the client is incapable of handling images as it is
   text-only, the algorithm above would have it save to disc.

13.  Representation of Gopher Addresses

   This section is greatly indebted to RFC 4266 [RFC4266].

   A Gopher address, or uniform resource locator, takes the form:

   gopher://<host>:<port>/<gopher-path>

   where <gopher-path> is one of:

   o  <gophertype><selector>

   o  <gophertype><selector>%09<search>

   o  <gophertype><selector>%09<search>%09<gopher+_string>



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   If :<port> is omitted, the port defaults to 70. <gophertype> is a
   single-character field to denote the Gopher type of the resource to
   which the URL refers.  The entire <gopher-path> may also be empty, in
   which case the delimiting `/` is also optional and the <gophertype>
   defaults to `1`.

   <selector> is the Gopher selector string.  Selector strings are
   arbitrary sequences of characters; they MUST NOT, however, contain
   the characters corresponding to horizontal tab, line feed, or
   carriage return.  Gopher clients specify which item to retrieve by
   sending the Gopher selector string to a Gopher server.  It is
   important to know that within the <gopher-path> itself, there are no
   reserved characters, so one may be arbitrarily creative when creating
   selector names.

   Note that some Gopher <selector> strings begin with a copy of the
   <gophertype> character, in which case that character will occur twice
   consecutively.  The Gopher selector string may be an empty string;
   this is how Gopher clients refer to the top-level directory on a
   Gopher server.

   If the URL refers to a search to be submitted to a Gopher search
   engine, the selector is followed by an encoded tab `%09` and the
   search string.  To submit a search to a Gopher search engine, the
   Gopher client sends the <selector> string (after decoding), a tab,
   and the search string to the Gopher server.

14.  Gopher Policy Files

   It is often useful to provide information to Gopher clients that MAY,
   but need not, be read by a human being.  It is for this reason that
   policy files exist.  This document enumerates two types of policy
   files, formally known as the Capability Policy and the Robot Access
   Restriction Policy, but also informally known under their filenames:
   `caps.txt` and `robots.txt`, respectively.

14.1.  Capability Policy

   It is RECOMMENDED, when hosting a public-access Gopher server, to
   include a capability policy.  Although it is, ultimately, the choice
   of the owner or operator of the server, a capability policy (or caps
   file) can be useful for clients querying the server for certain
   information without using extensions such as Gopher+.

   The purpose of a capability policy is so that a server can instruct a
   client on how properly to parse selectors in its filesystem; it
   ensures that the client can understand how files on the server are
   organised.  The scheme used in the current implementation of caps can



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   handle POSIX (UNIX and related operating systems), FAT/NTFS (used by
   Microsoft Windows), and HFS (used by all versions of Apple Mac OS,
   including OS X, which is otherwise POSIX-compatible).  For technical
   reasons, capability policies cannot handle VMS or Files-11 paths;
   however, owing to their open interface, the specification can be
   arbitrarily extended.

   A capability policy is quite simple in its composition: it is a plain
   text file with no more than seventy characters per line in the root
   directory of a Gopher server with the name

   caps.txt

   and beginning with the six characters

   CAPS[CR][LF]
   caps.txt

   Because of the constrained name and location of the policy, it is a
   trivial matter to verify if one exists or not; the address is always
   of the form <gopher://gopher.example.com/1/caps.txt>, with the real
   name of the server substituting for `example`. The server should
   accept both `caps.txt` and `/caps.txt` as selectors, and return the
   same content for both.

   A caps file contains *keys*, *values*, and *comments*.

   Keys can be compared to labelled containers for data; for instance,
   the key `ServerSoftware` is a container for the name of the Gopher
   software running on the server.  Keys in capability policies are
   always alphanumeric (i.e., composed of letters and numbers only) and
   generally are in CamelCase (each individual word within the key
   capitalised).  The data in these containers is called a value; values
   can use letters, numbers, and symbols.  Keys and values are connected
   by the equals (=) sign.  Any amount of whitespace (spaces and tabs)
   around the equals sign is acceptable.

   Anything not conforming to the syntax

   SomeKey = Value

   is ignored (treated as a comment).  To be compliant with GopherII,
   comments must begin with a hash (#) sign.  More importantly, they
   must be on a line to their own.

   Below is an example caps file.





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    CAPS
    CapsVersion=1
    ExpireCapsAfter=3600

    PathDelimeter=/
    PathIdentity=.
    PathParent=..
    PathParentDouble=FALSE
    PathEscapeCharacter=\\
    PathKeepPreDelimeter=FALSE

    ServerSoftware=Bucktooth
    ServerSoftwareVersion=0.2.9
    ServerArchitecture=AIX
    ServerDescription=IBM Power 520 Express, 2x4.2GHz POWER6 CPU, 8G RAM
    ServerGeolocationString=Southern California, USA

    ServerSupportsStdinScripts=TRUE

    ServerAdmin=gopher@floodgap.com

    DefaultEncoding=utf-8


   The `CapsVersion` field is self-explanatory, with one note: it should
   always be the *first* field in the file, so that an incompatible
   later format might be detected by the client.  The `ExpireCapsAfter`
   field tells the client the recommended cache expiry time (that is,
   the time between fetching and re-fetching the caps file) in
   *seconds*.  `3600` as above means one hour, and so on.

   The `Path` variables `PathDelimeter` [sic!], `PathIdentity`,
   `PathParent`, `PathParentDouble`, `PathEscapeCharacter`, and
   `PathKeepPreDelimeter` [sic!] refer to attributes of the file system.
   The above example is correct for a UNIX system, including Mac OS X.
   `PathDelimeter` refers to how the server separates folders from each
   other; Unix machines use `/`, Microsoft machines use `\`, and
   obsolete Macs use `:`.  `PathIdentity` refers to the shorthand used
   by an operating system to mean "this directory"; UNIX machines use
   `.`.  `PathParent` refers to the shorthand for "the directory
   immediately above", and is `..` on UNIX and Microsoft systems.
   `PathParentDouble` refers to an oddball feature of obsolete Macs: two
   consecutive path delimiters are used to refer to the parent
   directory.  For all systems other than pre-OS X Macintoshes,
   `PathParentDouble` should be FALSE.  `PathEscapeCharacter` tells the
   client the escape character for quoting delimiters when they appear
   in selectors; most of the time, this is `\\`.  `PathKeepPreDelimiter`




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   tells the client not to cut everything up to the first path
   delimiter; most of the time, this should be `FALSE`.

   The `Server` variables `ServerSoftware`, `ServerSoftwareVersion`,
   `ServerArchitecture`, `ServerDescription`, and
   `ServerGeolocationString` are freetext descriptions of the server
   software and version, operating system ("architecture"), server
   hardware (`Server Description`), and location on the Earth.

   Finally, `ServerAdmin` is an eMail contact address for the server
   administrator, and `DefaultEncoding` is the default text encoding for
   content types 0 and 1.

14.2.  Robot Access Restrictions Policy

   WWIS robots, also known as spiders, crawlers, or wanderers, are
   computer programmes that, without human intervention, recursively
   travel throughout linked pages or directories on an information
   system (that is, by repeatedly travelling up and down a tree) and
   store the copies of these files at an independent location.  The
   process of programmatically gathering information in this manner is
   called crawling or spidering.

   Many sites, in particular search engines (such as Google on the World
   Wide Web, or Veronica on Gopher), use spidering as a means of
   providing up-to-date data.  Robots are mainly used to create a copy
   of all the visited pages for later processing by a search engine that
   will index the downloaded pages to provide fast searches.  Robots can
   also be used for redundancy; data can be preserved by a third party
   in case the original server becomes inaccessible.

   In 1993 and 1994, however, there were occasions where robots had
   visited locations on the Web at which they were not welcome.
   Inexperienced or heavy-handed use of robots caused situations where
   servers were swamped with requests at a high rate of speed; or, the
   same files were retrieved repeatedly.  Both could cause denial of
   service.  In other situations, robots traversed parts of servers that
   were unsuitable, such as temporary information or server-side
   scripts, especially those with side-effects (such as polls).  Abuse
   of robots was also an issue, and continues to be one now; for
   instance, electronic mail addresses have been harvested with knowing
   intent to distribute unsolicited mail ('spam').

   These incidents indicated the need for established mechanisms for
   Gopher servers to indicate to robots which parts of their server
   should not be accessed.  This specification addresses this
   requirement with an operational solution, adapted from the identical




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   method used on sites using the Hypertext Transfer and File Transfer
   Protocols.

   The method used to exclude robots from a Gopher server is formally
   known as the Robot Access Restrictions Policy (RARP) and consists of
   placing a plain-text file specifying, in simple and user-friendly
   syntax, which robots may access which directory.  The policy file, if
   it exists, MUST be accessible via Gopher on the local address

   /robots.txt

   A possible drawback of this single-file approach is that only a
   server administrator can maintain such a list, not the individual
   document maintainers on the server.  This can be resolved by a local
   process to construct the single file from a number of others, but if,
   or how, this is done is outside of the scope of this document.

   Furthermore, Gopher administrators should bear in mind that the Robot
   Access Restrictions Policy works largely on the honour system.  Many
   crawlers can be set to ignore the policy, and it is trivial to write
   this capability into a new crawler.

   The policy file consists of one or more records, separated by one or
   more blank lines, terminated by the Gopher-standard CR/LF.  Each
   record contains two or more lines of the form

   <field>:<value>

   The field name is not case-sensitive.  Comments (lines to be ignored
   by robots themselves, but useful to robot operators and others) start
   with the hash (#) character and end with the line terminator (CR/LF).
   A value can share a line with a comment.  A record starts with at
   least one `User-agent` field, followed by at least one `Disallow`
   field.  There are two further, optional fields: `Crawl-delay`, as
   well as `Allow`.

   The value of the `User-agent` field is the name of the robot whose
   access policy is being described.  If more than one `User-agent`
   field is present, the record is describing an identical access policy
   for each robot.  This field is to be interpreted broadly.  The
   recommended implementation of access policies in the robot's code is
   for a case-insensitive sub-string match, without version information.
   Since one is describing an access policy for at least one robot, at
   least one `User-agent` field is required.  The value `*` (quotes
   excluded) describes access policy for any robot not matching any
   previous records; therefore, if listed, it SHOULD be listed last of
   all.  If it is not listed last of all, anything below it will be
   ignored.



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   The value of the `Disallow` field specifies a partial URL that is not
   to be visited.  This can be a full path, or a partial path.  Any
   address that begins with this value will not be retrieved; for
   instance, the line Disallow: /help would disallow `/help/index.html`;
   `/help/faq.html`; as well as `/help.html`.  Conversely, the line
   Disallow: /help/ would allow `/help.html`, but nothing in the
   directory `/help/`.  An empty `Disallow` field indicates that all
   addresses can be retrieved.  As one is defining policy and not simply
   listing the names of robots, at least one `Disallow` field is
   required per record.

   One can also add specific exceptions to the locations disallowed by
   using the `Allow` field.

   The `Crawl-delay` field is also supported; this field indicates the
   number of seconds to wait between successive requests to the same
   server; the value must be an integer with no units.

   The following is an example of a well-built policy file: # Robot
   Exclusion File for gopher://gopher.scdp.com # If you wish to crawl
   gopher.scdp.com, please contact # lane.pryce@scdp.com to apply for an
   exemption.  Our terms of # service are available at
   gopher://gopher.scdp.com/0/tos.txt.  User-agent: baiduspider User-
   agent: googlebot User-agent: msnbot User-agent: bingbot User-agent:
   naverbot User-agent: seznambot User-agent: slurp User-agent: teoma
   User-agent: yandex Disallow: /cgi-bin/ # Dynamically generated
   scripts Disallow: /images/ # This consumes bandwidth!  Disallow:
   /tmp/ # Temporary files---blink, gone!  Disallow: /private/ # No
   peeking!  Allow: /images/logo.jpg # Main logo.  Mirror this if
   possible.  Crawl-delay: 10 User-agent: * Disallow: / # If you have
   received authorisation to crawl this site, and are # getting denied,
   please contact support@scdp.com, or dial # (212) 555 0169.  This site
   is copyright Sterling, Cooper, Draper, # and Pryce, 2012.

   In plain terms, this server allows major search engines Baidu,
   Google, Bing, Naver, Seznam, Teoma, Yahoo, and Yandex to mirror the
   site freely, with the exception of everything in the directories
   /cgi-bin/, /tmp/, and /private/, as well as everything with the
   exception of the single file logo.jpg in the directory /images/.  So
   as to not unduly slow the server down, the policy file requests that
   search engines wait ten seconds between requests.  All other robots
   are prohibited from accessing the site.

   Examples such as the following SHOULD NOT be used except in very rare
   situations.  Robots generally cause more good than harm, and
   excluding them entirely, as this anti-social user would, does not
   make Gopher a healthy place.




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   # Piss off!
   User-agent: *
   Disallow: /

14.3.  Administrator Contact File

   It is worth remembering that computers, like anything else, are
   fallible and prone to error.  When failure occurs in Gopherspace, the
   person in the best position to rectify it is the system
   administrator.  Furthermore, users may have questions or comments,
   also best directed to the system administrator.  For this reason,
   each Gopher server MUST have a file in its top-level directory with
   the name *about.txt* and a RECOMMENDED selector string of *About* or
   *About this server* (equivalents in the local language are
   permissible, but an English translation is similarly RECOMMENDED).
   It is the Gopher equivalent of a Unix user's finger output.

   Since this file is intended to be readable by humans and not
   computers, it does not have a defined file format.  However, it
   should have a short description of the server's contents, as well as
   the contact details of the server administrator and any other key
   employees, such as the legal department.  A well-structured contact
   file looks as follows:




























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      Sterling|Cooper|Draper|Pryce
      ============================

      Welcome to SCDP!  We are a full-service advertising and marketing
      agency staffed by a team of diverse, senior professionals with a
      flair for solid strategy and compelling creative output. Our team
      produces unique television, radio, print, and Web advertisements
      for a range of industries.

      Our ability to identify and communicate your greatest benefit to
      your customers is our greatest benefit to you. We find out what
      makes you truly unique. We have built an excellent team: each
      member is an advertising specialist in their own right.
      Photography, programming, writing, design, strategy---you name it,
      we have a creative for that.

      System Administrator: Margaret Olson
      Telephone:            (212) 555 0169 x808
      Address:              13, Madison Avenue,
                            New York, N.Y.,
                            U.S.A.
      eMail:                peggy.olson@scdp.com
      Skype:                peggyXolson

      All prospective clients:
      Please contact Creative Director Donald Draper at extension 069.

      Legal issues:
      For all legal and financial issues, please contact Lane Pryce
      at extension 777.

15.  IANA Considerations

   Nothing within this document should be taken to imply that any
   actions are to be undertaken by the Internet Assigned Numbers
   Authority.

16.  Security Considerations

   Security in GopherII is dependent on the connexion on which it runs.
   Standard GopherII (that is, running on "straight" TCP) is insecure
   simply by virtue of the protocol.  Sensitive information, such as
   credit card numbers, must not be sent over a standard Gopher link.
   It is permissible to run GopherII over SSL, in which case all
   security considerations that apply for working HTTPS apply also for
   GopherIIs.





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17.  Acknowledgements

   Thanks go to John Klensin for his invaluable assistance in regards to
   the IETF process, his constructive criticism, and his calm demeanour
   even when others just could not keep their tempers in check.

   Thanks also go to the members of the Gopher mailing list for keeping
   the Gopher protocol alive.  Thanks go specifically to the Gopher
   developers: to Matjaz Mesnjak for his Windows-compatible, graphical
   Gopher client and his simple Motsognir Gopher server; to Dr Cameron
   Kaiser for Veronica-II, the next generation of Gopher search engine,
   for the Bucktooth Gopher server, for the Overbite extension for
   Mozilla Firefox, and for his tireless work on GopherVR, the only full
   virtual-reality Gopher client; to Kevin Veroneau for his Gopher
   Application Framework; and to Kim Holviala for the Gophernicus Gopher
   server.

   Finally, my thanks go to Thomas E.  Dickey and the others who have
   put in valuable work on the Lynx browser.  I thank them because,
   rather than remove Gopher support in a misguided attempt to plug
   security holes, they have in fact continued to improve this side of
   their software, and they have succeeded in making the finest text-
   mode Gopher client bar none.

18.  References

18.1.  Normative References

   [Anklesaria1993]
              Anklesaria, F., "Gopher+: upward compatible enhancements
              to the Internet Gopher protocol", 1993.

              Anklesaria, Farhad; Lindner, Paul; McCahill, Mark P.;
              Torrey, Daniel; Johnson, David; Alberti, Bob (1993). **
              Retrieved 23 May, 2012, from
              <gopher://gophernicus.org/0/doc/gopher/gopher+.txt>

   [RFC1436]  Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,
              Torrey, D., and B. Alberti, "The Internet Gopher Protocol
              (a distributed document search and retrieval protocol)",
              RFC 1436, March 1993.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.







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18.2.  Informative References

   [CapsRef]  Kaiser, C., "Welcome to caps!", 2010.

              Kaiser, Cameron (2010). *Welcome to caps!* Retrieved 23
              May, 2012, from <gopher://gophernicus.org/0/doc/gopher/
              gopher-caps.txt>

   [Floodgap]
              Floodgap, "Floodgap's caps file".

              <gopher://gopher.floodgap.com/0/caps.txt> - Floodgap's
              caps file

   [Goerzen2012]
              Goerzen, J., "Links to URL", 2002.

              Goerzen, John (2002). *Links to URL.* Retriever 23 May,
              2012, from <gopher://gophernicus.org/0/doc/gopher/
              hURL.txt>

   [GopherHistory]
              ??, ?., "A paper on the history of Gopher".

              <gopher://jgw.mdns.org/9/REFS/56817068-PIL3254-Internet-
              Gopher-PPL- Alberti.pdf> -- A paper on the history of
              Gopher

   [RelatedDocs]
              ??, ?., "gophernicus.org".

              <gopher://gophernicus.org/1/doc/gopher/> - A number of
              documents relating to gopher, including the RFCs

   [RFC4266]  Hoffman, P., "The gopher URI Scheme", RFC 4266, November
              2005.

   [UpdatedGopher]
              ??, ?., "The "Updated Gopher RFC" thread", 2012.

              The "Updated Gopher RFC" thread (started May 8 2012) on
              the gopher-project mailing list

Appendix A.  Summary of Changes from RFC 1436

   In broad strokes, RFC 1436 is compatible with this document; an "old"
   Gopher client should be fully capable of browsing a GopherII server.
   GopherII can be considered simply a refinement of the RFC 1436



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   concept; while RFC 1436 lays out a viable protocol, it leaves a lot
   of small-scale implementation detail up to the makers of client
   software.  While a sort of gentleman's agreement did manifest itself,
   and while this gentleman's agreement was in some places almost
   universal (the `i` itemtype, for example, with only Microsoft
   Internet Explorer as the nonconforming Gopher client) it did lack
   standardisation, which is what this document remedies.  More
   specifically:

   o  c, d, h, i, p, m, s, x, ; itemtypes.

   o  extension formerly known as Gopher+

   o  terminating full-stop behaviour

   o  what to put in the title bar (`TITLE` resource)

   o  links to HTTP urls

   o  policy files

Appendix B.  Change Log

B.1.  Changes from -00 to -01 of this specification

   Converted to RFC standard format for legibility; added security
   considerations section.

B.2.  Changes from -01 to -02 of this specification

   Added acknowledgements and changes from original Gopher RFC's.
   Removed placeholder text.

Authors' Addresses

   Ted Matavka

   Email: n.theodore.matavka.files@gmail.com


   Wolfgang Faust

   Email: wolfgangmcq@gmail.com








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