Unicode Separated Values (USV)
draft-unicode-separated-values-01

Internet Engineering Task Force                        J. Henderson, Ed.
Internet-Draft                                             16 March 2024
Intended status: Experimental                                           
Expires: 17 September 2024

                     Unicode Separated Values (USV)
                   draft-unicode-separated-values-01

Abstract

   Unicode Separated Values (USV) is a data format that uses Unicode
   characters to mark parts.  USV builds on ASCII separated values
   (ASV), and provides pragmatic ways to edit data in text editors by
   using visual symbols and layouts.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 17 September 2024.

Copyright Notice

   Copyright (c) 2024 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
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Media Type Language . . . . . . . . . . . . . . . . . . .   3
     1.3.  ABNF Language . . . . . . . . . . . . . . . . . . . . . .   3
   2.  USV characters  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Definition of the USV Format  . . . . . . . . . . . . . . . .   4
     3.1.  Data  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Unit  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Record  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.4.  Group . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.5.  File  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.6.  Header  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.7.  Escape (ESC)  . . . . . . . . . . . . . . . . . . . . . .   5
     3.8.  End of Transmission (EOT) . . . . . . . . . . . . . . . .   5
   4.  ABNF grammar  . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Semantics . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Runs  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.4.  Character classes . . . . . . . . . . . . . . . . . . . .   6
     4.5.  Unicode symbols . . . . . . . . . . . . . . . . . . . . .   6
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Hello World . . . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Hello World Goodnight Moon  . . . . . . . . . . . . . . .   7
     5.3.  Units, Records, Groups, Files . . . . . . . . . . . . . .   8
     5.4.  Articles  . . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Source Code Examples  . . . . . . . . . . . . . . . . . . . .  10
   7.  MIME media type registration for text/usv . . . . . . . . . .  10
     7.1.  Optional parameters: charset, header  . . . . . . . . . .  11
     7.2.  Encoding considerations . . . . . . . . . . . . . . . . .  11
     7.3.  Security considerations . . . . . . . . . . . . . . . . .  11
     7.4.  Interoperability considerations . . . . . . . . . . . . .  11
     7.5.  Published specification . . . . . . . . . . . . . . . . .  11
     7.6.  Applications that use this media type . . . . . . . . . .  11
     7.7.  Additional information  . . . . . . . . . . . . . . . . .  12
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     10.2.  Informative References . . . . . . . . . . . . . . . . .  13
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  13
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

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1.  Introduction

   Unicode Separated Values (USV) is a data format useful for exchanging
   and converting data between various spreadsheet programs, databases,
   and streaming data services.  This RFC explains USV.

   Additionally, we propose a new media type "text/usv", to be
   registered with IANA.

   We provide information references for a USV git repository
   [usv-git-repository] and a programming implementation as a USV Rust
   crate [usv-rust-crate].

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  Media Type Language

   The media type normative references are RFC 6838 [RFC6838], RFC 2046
   [RFC2046], and RFC 4289 [RFC4289].

1.3.  ABNF Language

   The ABNF normative reference is RFC 5234 [RFC5234].

2.  USV characters

   Separators:

   *  File Separator (FS) is U+001C or U+241C

   *  Group Separator (GS) is U+001D or U+241D

   *  Record Separator (RS) is U+001E or U+241E

   *  Unit Separator (US) is U+001F or U+241F

   Modifiers:

   *  Escape (ESC) is U+001B or U+241B

   *  End of Transmission (EOT) is U+0004 or U+2404

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   Liners:

   *  Carriage Return (CR) is U+000D

   *  Line Feed (LF) is U+000A

3.  Definition of the USV Format

3.1.  Data

   Data comprises units, records, groups, and files.

3.2.  Unit

   A unit comprises content characters.  It runs until a Unit Separator
   (US):

   Example unit and unit separator:

   <CODE BEGINS> file "unit-and-unit-separator.usv"
   aaa␟
   <CODE ENDS>

3.3.  Record

   A record comprises units.  It runs until a Record Separator (RS):

   Example record and record separator:

   <CODE BEGINS> file "record-and-record-separator.usv"
   aaa␟bbb␟␞
   <CODE ENDS>

3.4.  Group

   A group comprises records.  It runs until a Group Separator (GS):

   Example group and group separator:

   <CODE BEGINS> file "group-and-group-separator.usv"
   aaa␟bbb␟␞ccc␟ddd␟␞␝
   <CODE ENDS>

3.5.  File

   A file comprises groups.  It runs until a file separator.

   Example file and file separator:

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   <CODE BEGINS> file "file-and-file-separator.usv"
   aaa␟bbb␟␞ccc␟ddd␟␞␝eee␟fff␟␞ggg␟hhh␟␞␝␜
   <CODE ENDS>

3.6.  Header

   There may be an optional header appearing as the first item and with
   the same format as normal items.  This header will contain names
   corresponding to the fields in the data, and should contain the same
   number of fields as the rest of data.  The presence or absence of the
   header line should be indicated via the optional "header" parameter
   of this media type.

   For example:

   <CODE BEGINS> file "header.usv"
   name␟name␟␞aaa␟bbb␟␞
   <CODE ENDS>

3.7.  Escape (ESC)

   Escape (ESC) makes the next character content.

   Example: USV with a unit that contains an Escape + End of
   Transmission; because of the Escape, the End of Transmission is
   treated as content:

   <CODE BEGINS> file "header.usv"
     a␛␄b␟
   <CODE ENDS>

3.8.  End of Transmission (EOT)

   End of Transmission (EOT) tells any reader that it can stop reading.
   This is can be useful for streaming data, such as to end a
   connection.  This can also be useful for providing data files that
   contain USV data, then EOT, then addition non-USV information such as
   comments, images, attachments, etc.

   *  EOT tells the data reader that it can stop.

   *  EOT has no effect on the output content.

   Example of a unit then an End of Transmission:

   <CODE BEGINS> file "header.usv"
   abc␞␄ignorable
   <CODE ENDS>

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4.  ABNF grammar

4.1.  Semantics

   usv = *files

   file = *groups

   group = *records

   record = *units

   unit = *content-characters

4.2.  Syntax

   usv = ( header-and-body / body ) '*' ; anything after the body is
   chaff

   header-and-body = 1*unit-run / 1*record-run / 1*group-run / 1*file-
   run

   body = *unit-run / *record-run / *group-run / *file-run

4.3.  Runs

   file-run = *( *liner-character file *liner-character FS )

   group-run = *( *liner-character group *liner-character GS )

   record-run = *( *liner-character record *liner-character RS )

   unit-run = *( *liner-character unit *liner-character US )

4.4.  Character classes

   content-character = typical-character / ESC '*'

   typical-character = '*' - special-character

   special-character = US / RS / GS / FS / ESC / EOT

   liner-character = CR / LF

4.5.  Unicode symbols

   FS = U+001C File Separator / U+241C Symbol for File Separator

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   GS = U+001D Group Separator / U+241D Symbol for Group Separator

   RS = U+001E Record Separator / U+241E Symbol for Record Separator

   US = U+001F Unit Separator / U+241F Symbol for Unit Separator

   ESC = U+001B Escape / U+241B Symbol for Escape

   EOT = U+0004 End of Transmission / U+2404 Symbol for End of
   Transmission

   CR = U+000D Carriage Return

   LF = U+000A Line Feed

5.  Examples

5.1.  Hello World

   This kind of data …

   <CODE BEGINS> file "hello-world.txt"
   hello, world
   <CODE ENDS>

   … is represented in USV as two units:

   <CODE BEGINS> file "hello-world.usv"
   hello␟world␟
   <CODE ENDS>

   If you prefer to see one unit per line, then you can add carriage
   returns and/or newlines:

   <CODE BEGINS> file "hello-world-with-lines.usv"
   hello␟
   world␟
   <CODE ENDS>

5.2.  Hello World Goodnight Moon

   This kind of data …

   <CODE BEGINS> file "hello-world-goodnight-moon.txt"
   [ hello, world ], [ goodnight, moon ]
   <CODE ENDS>

   … is represented in USV as two records, each with two units:

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   <CODE BEGINS> file "hello-world-goodnight-moon.usv"
   hello␟world␟␞goodnight␟moon␟␞
   <CODE ENDS>

   If you prefer to see one record per line, then you can add carriage
   returns and/or newlines:

   <CODE BEGINS> file "hello-world-goodnight-moon-with-lines.usv"
   hello␟world␟␞
   goodnight␟moon␟␞
   <CODE ENDS>

5.3.  Units, Records, Groups, Files

   USV with 2 units by 2 records by 2 groups by 2 files:

   <CODE BEGINS> file "units-records-groups-files.usv"
   a␟b␟␞c␟d␟␞␝e␟f␟␞g␟h␟␞␝␜i␟j␟␞k␟l␟␞␝m␟n␟␞o␟p␟␞␝␜
   <CODE ENDS>

   If you prefer to see one record per line, then you can add carriage
   returns and/or newlines:

   <CODE BEGINS> file "units-records-groups-files-with-lines.usv"
   a␟b␟␞
   c␟d␟␞
   ␝
   e␟f␟␞
   g␟h␟␞
   ␝
   ␜
   i␟j␟␞
   k␟l␟␞
   ␝
   m␟n␟␞
   o␟p␟␞
   ␝
   ␜
   <CODE ENDS>

   If you prefer to see one unit per line, then you can add carriage
   returns and/or newlines:

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   <CODE BEGINS> file "units-records-groups-files-with-lines.usv"
   a␟
   b␟
   ␞
   c␟
   d␟
   ␞
   ␝
   e␟
   f␟
   ␞
   g␟
   h␟
   ␞
   ␝
   ␜
   i␟
   j␟
   ␞
   k␟
   l␟
   ␞
   ␝
   m␟
   n␟
   ␞
   o␟
   p␟
   ␞
   ␝
   ␜
   <CODE ENDS>

5.4.  Articles

   USV can format paragraphs, such as in this example data stream of
   articles; note the units contain leading liners and trailing liners.

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   <CODE BEGINS> file "articles.usv"
   Title One
   ␟
   Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
   tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
   veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip.
   ␟␞
   Title Two
   ␟
   Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore
   eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident,
   sunt in culpa qui officia deserunt mollit anim id est laborum.
   ␟␞
   Title Three
   ␟
   Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
   doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore
   veritatis et quasi architecto beatae vitae dicta sunt explicabo.
   ␟␞
   <CODE ENDS>

6.  Source Code Examples

   Hello World using Rust and the USV crate

   <CODE BEGINS> file "usv-rust-crate-units.rs"
   use usv::*;
   let input = "hello␟world␟";
   let units = input.units().collect();
   <CODE ENDS>

   Hello World Goodnight Moon using Rust and the USV crate

   <CODE BEGINS> file "usv-rust-crate-records.rs"
   use usv::*;
   let input = "hello␟world␟␞goodnight␟moon␟␞";
   let records = input.records().collect();
   <CODE ENDS>

7.  MIME media type registration for text/usv

   This section provides the MIME media type registration application
   information.

   To: ietf-types@iana.org

   Subject: Registration of MIME media type text/usv

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   MIME media type name: text

   MIME subtype name: usv

   Required parameters: none

7.1.  Optional parameters: charset, header

   Common usage of USV is UTF-8, but other character sets defined by
   IANA for the "text" tree may be used in conjunction with the
   "charset" parameter.

   The "header" parameter indicates the presence or absence of the
   header line.  Valid values are "present" or "absent".  Implementors
   choosing not to use this parameter must make their own decisions as
   to whether the header line is present or absent.

7.2.  Encoding considerations

   This media type uses LF to denote line breaks.  However, implementors
   should be aware that some implementations may not conform i.e. may
   incorrectly use other values.

7.3.  Security considerations

   USV files contain passive text data that should not pose any risks.
   However, it is possible in theory that malicious binary data may be
   included in order to exploit potential buffer overruns in the program
   processing USV data.  Additionally, private data may be shared via
   this format (which of course applies to any text data).

7.4.  Interoperability considerations

   Implementors should "be conservative in what you do, be liberal in
   what you accept from others" (RFC 793 [8]) when processing USV data.

   Implementations deciding not to use the optional "header" parameter
   must make their own decision as to whether the header is absent or
   present.

7.5.  Published specification

   https://github.com/sixarm/usv

7.6.  Applications that use this media type

   Spreadsheet programs, such as with import/export.  Database programs,
   such as with loading/saving text.  Data conversion utilities.

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7.7.  Additional information

   Magic number(s): none

   File extension(s): usv

   Apple macOS File Type Code(s): TEXT

   Intended usage: COMMON

   Author/Change controller: IESG

   Contact: Joel Parker Henderson <joel@joelparkerhenderson.com>

8.  IANA Considerations

   We are requesting IANA to create a standard MIME media type "text/
   usv".

   We have filed an IANA request for this, with same contact
   information.

9.  Security Considerations

   This document should not affect the security of the Internet.

10.  References

10.1.  Normative References

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              DOI 10.17487/RFC2046, November 1996,
              <https://www.rfc-editor.org/info/rfc2046>.

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   [RFC4289]  Freed, N. and J. Klensin, "Multipurpose Internet Mail
              Extensions (MIME) Part Four: Registration Procedures",
              BCP 13, RFC 4289, DOI 10.17487/RFC4289, December 2005,
              <https://www.rfc-editor.org/info/rfc4289>.

10.2.  Informative References

   [usv-git-repository]
              Henderson, J., "USV git repository at
              https://github.com/sixarm/usv", 2022.

   [usv-rust-crate]
              Henderson, J., "USV rust crate at
              https://crates.io/crates/usv", 2024.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

Acknowledgements

   The author would like to thank Y.  Shafranovich, author of the CSV
   RFC, which provided guidance for this USV RFC.

   A special thank you goes to P.X.V.

Contributors

   Thanks to all of the contributors.

   Joel Parker Henderson
   Email: joel@joelparkerhenderson.com

Author's Address

   Joel Parker Henderson (editor)
   601 Van Ness Ave #E3-359
   San Francisco, CA 94102
   United States of America
   Phone: 1-415-317-2700
   Email: joel@joelparkerhenderson.com
   URI:   https://linkedin.com/in/joelparkerhenderson

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