| Internet-Draft | Unicode Separated Values (USV) | March 2024 |
| Henderson | Expires 17 September 2024 | [Page] |
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.¶
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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].¶
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.¶
The media type normative references are RFC 6838 [RFC6838], RFC 2046 [RFC2046], and RFC 4289 [RFC4289].¶
Separators:¶
Modifiers:¶
Liners:¶
Data comprises units, records, groups, and files.¶
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>¶
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>¶
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>¶
A file comprises groups. It runs until a file separator.¶
Example file and file separator:¶
<CODE BEGINS> file "file-and-file-separator.usv" aaa␟bbb␟␞ccc␟ddd␟␞␝eee␟fff␟␞ggg␟hhh␟␞␝␜ <CODE ENDS>¶
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>¶
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>¶
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.¶
Example of a unit then an End of Transmission:¶
<CODE BEGINS> file "header.usv" abc␞␄ignorable <CODE ENDS>¶
usv = *files¶
file = *groups¶
group = *records¶
record = *units¶
unit = *content-characters¶
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¶
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 )¶
content-character = typical-character / ESC '*'¶
typical-character = '*' - special-character¶
special-character = US / RS / GS / FS / ESC / EOT¶
liner-character = CR / LF¶
FS = U+001C File Separator / U+241C Symbol for File Separator¶
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¶
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>¶
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:¶
<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>¶
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:¶
<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>¶
USV can format paragraphs, such as in this example data stream of articles; note the units contain leading liners and trailing liners.¶
<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>¶
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>¶
This section provides the MIME media type registration application information.¶
To: ietf-types@iana.org¶
Subject: Registration of MIME media type text/usv¶
MIME media type name: text¶
MIME subtype name: usv¶
Required parameters: none¶
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.¶
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.¶
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).¶
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.¶
https://github.com/sixarm/usv¶
Spreadsheet programs, such as with import/export. Database programs, such as with loading/saving text. Data conversion utilities.¶
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>¶
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.¶
This document should not affect the security of the Internet.¶
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.¶
Thanks to all of the contributors.¶