Movatterモバイル変換

Network Working Group                                    Y. ShafranovichRequest for Comments: 4180                SolidMatrix Technologies, Inc.Category: Informational                                     October 2005Common Format and MIME Type for Comma-Separated Values (CSV) FilesStatus of This Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2005).Abstract   This RFC documents the format used for Comma-Separated Values (CSV)   files and registers the associated MIME type "text/csv".Table of Contents1. Introduction ....................................................22. Definition of the CSV Format ....................................23. MIME Type Registration of text/csv ..............................44. IANA Considerations .............................................55. Security Considerations .........................................56. Acknowledgments .................................................67. References ......................................................67.1. Normative References .......................................67.2. Informative References .....................................6Shafranovich                 Informational                      [Page 1]

RFC 4180       Common Format and MIME Type for CSV Files    October 20051.  Introduction   The comma separated values format (CSV) has been used for exchanging   and converting data between various spreadsheet programs for quite   some time.  Surprisingly, while this format is very common, it has   never been formally documented.  Additionally, while the IANA MIME   registration tree includes a registration for   "text/tab-separated-values" type, no MIME types have ever been   registered with IANA for CSV.  At the same time, various programs and   operating systems have begun to use different MIME types for this   format.  This RFC documents the format of comma separated values   (CSV) files and formally registers the "text/csv" MIME type for CSV   in accordance withRFC 2048 [1].2.  Definition of the CSV Format   While there are various specifications and implementations for the   CSV format (for ex. [4], [5], [6] and [7]), there is no formal   specification in existence, which allows for a wide variety of   interpretations of CSV files.  This section documents the format that   seems to be followed by most implementations:   1.  Each record is located on a separate line, delimited by a line       break (CRLF).  For example:       aaa,bbb,ccc CRLF       zzz,yyy,xxx CRLF   2.  The last record in the file may or may not have an ending line       break.  For example:       aaa,bbb,ccc CRLF       zzz,yyy,xxx   3.  There maybe an optional header line appearing as the first line       of the file with the same format as normal record lines.  This       header will contain names corresponding to the fields in the file       and should contain the same number of fields as the records in       the rest of the file (the presence or absence of the header line       should be indicated via the optional "header" parameter of this       MIME type).  For example:       field_name,field_name,field_name CRLF       aaa,bbb,ccc CRLF       zzz,yyy,xxx CRLFShafranovich                 Informational                      [Page 2]

RFC 4180       Common Format and MIME Type for CSV Files    October 2005   4.  Within the header and each record, there may be one or more       fields, separated by commas.  Each line should contain the same       number of fields throughout the file.  Spaces are considered part       of a field and should not be ignored.  The last field in the       record must not be followed by a comma.  For example:       aaa,bbb,ccc   5.  Each field may or may not be enclosed in double quotes (however       some programs, such as Microsoft Excel, do not use double quotes       at all).  If fields are not enclosed with double quotes, then       double quotes may not appear inside the fields.  For example:       "aaa","bbb","ccc" CRLF       zzz,yyy,xxx   6.  Fields containing line breaks (CRLF), double quotes, and commas       should be enclosed in double-quotes.  For example:       "aaa","b CRLF       bb","ccc" CRLF       zzz,yyy,xxx   7.  If double-quotes are used to enclose fields, then a double-quote       appearing inside a field must be escaped by preceding it with       another double quote.  For example:       "aaa","b""bb","ccc"   The ABNF grammar [2] appears as follows:   file = [header CRLF] record *(CRLF record) [CRLF]   header = name *(COMMA name)   record = field *(COMMA field)   name = field   field = (escaped / non-escaped)   escaped = DQUOTE *(TEXTDATA / COMMA / CR / LF / 2DQUOTE) DQUOTE   non-escaped = *TEXTDATA   COMMA = %x2C   CR = %x0D ;as persection 6.1 of RFC 2234 [2]Shafranovich                 Informational                      [Page 3]

RFC 4180       Common Format and MIME Type for CSV Files    October 2005   DQUOTE =  %x22 ;as persection 6.1 of RFC 2234 [2]   LF = %x0A ;as persection 6.1 of RFC 2234 [2]   CRLF = CR LF ;as persection 6.1 of RFC 2234 [2]   TEXTDATA =  %x20-21 / %x23-2B / %x2D-7E3.  MIME Type Registration of text/csv   This section provides the media-type registration application (as perRFC 2048 [1].   To: ietf-types@iana.org   Subject: Registration of MIME media type text/csv   MIME media type name: text   MIME subtype name: csv   Required parameters: none   Optional parameters: charset, header      Common usage of CSV is US-ASCII, 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.   Encoding considerations:      As persection 4.1.1. of RFC 2046 [3], this media type uses CRLF      to denote line breaks.  However, implementors should be aware that      some implementations may use other values.   Security considerations:      CSV 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 CSV data.  Additionally, private data      may be shared via this format (which of course applies to any text      data).Shafranovich                 Informational                      [Page 4]

RFC 4180       Common Format and MIME Type for CSV Files    October 2005   Interoperability considerations:      Due to lack of a single specification, there are considerable      differences among implementations.  Implementors should "be      conservative in what you do, be liberal in what you accept from      others" (RFC 793 [8]) when processing CSV files.  An attempt at a      common definition can be found inSection 2.      Implementations deciding not to use the optional "header"      parameter must make their own decision as to whether the header is      absent or present.   Published specification:      While numerous private specifications exist for various programs      and systems, there is no single "master" specification for this      format.  An attempt at a common definition can be found inSection2.   Applications that use this media type:      Spreadsheet programs and various data conversion utilities   Additional information:      Magic number(s): none      File extension(s): CSV      Macintosh File Type Code(s): TEXT   Person & email address to contact for further information:      Yakov Shafranovich <ietf@shaftek.org>   Intended usage: COMMON   Author/Change controller: IESG4.  IANA Considerations   The IANA has registered the MIME type "text/csv" using the   application provided inSection 3 of this document.5.  Security Considerations   See discussion above insection 3.Shafranovich                 Informational                      [Page 5]

RFC 4180       Common Format and MIME Type for CSV Files    October 20056.  Acknowledgments   The author would like to thank Dave Crocker, Martin Duerst, Joel M.   Halpern, Clyde Ingram, Graham Klyne, Bruce Lilly, Chris Lilley, and   members of the IESG for their helpful suggestions.  A special word of   thanks goes to Dave for helping with the ABNF grammar.   The author would also like to thank Henrik Lefkowetz, Marshall Rose,   and the folks at xml.resource.org for providing many of the tools   used for preparing RFCs and Internet drafts.   A special thank you goes to L.T.S.7.  References7.1.  Normative References   [1]  Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet        Mail Extensions (MIME) Part Four: Registration Procedures",BCP13,RFC 2048, November 1996.   [2]  Crocker, D. and P. Overell, "Augmented BNF for Syntax        Specifications: ABNF",RFC 2234, November 1997.   [3]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail        Extensions (MIME) Part Two: Media Types",RFC 2046, November        1996.7.2.  Informative References   [4]  Repici, J., "HOW-TO: The Comma Separated Value (CSV) File        Format", 2004,        <http://www.creativyst.com/Doc/Articles/CSV/CSV01.htm>.   [5]  Edoceo, Inc., "CSV Standard File Format", 2004,        <http://www.edoceo.com/utilis/csv-file-format.php>.   [6]  Rodger, R. and O. Shanaghy, "Documentation for Ricebridge CSV        Manager", February 2005,        <http://www.ricebridge.com/products/csvman/reference.htm>.   [7]  Raymond, E., "The Art of Unix Programming, Chapter 5", September        2003,        <http://www.catb.org/~esr/writings/taoup/html/ch05s02.html>.   [8]  Postel, J., "Transmission Control Protocol", STD 7,RFC 793,        September 1981.Shafranovich                 Informational                      [Page 6]

RFC 4180       Common Format and MIME Type for CSV Files    October 2005Author's Address   Yakov Shafranovich   SolidMatrix Technologies, Inc.   EMail: ietf@shaftek.org   URI:http://www.shaftek.orgShafranovich                 Informational                      [Page 7]

RFC 4180       Common Format and MIME Type for CSV Files    October 2005Full Copyright Statement   Copyright (C) The Internet Society (2005).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at ietf-   ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Shafranovich                 Informational                      [Page 8]