- From: Markus Scherer <markus.scherer@jtcsv.com>
- Date: Thu, 15 Jun 2000 08:41:26 -0700
- To: charsets <ietf-charsets@iana.org>
(This is an updated proposal that incorporates feedback from Kenneth Whistler, Harald Tveit Alvestrand, and Martin J. Dürst.) Charset name: SCSU Charset aliases: (none, except for the implicit csSCSU) Suitability for use in MIME text: No Published Specification: Unicode Technical Report #6 "A Standard Compression Scheme for Unicode" http://www.unicode.org/unicode/reports/tr6/ CCS & CES: The SCSU charset is a combination of the Unicode and ISO 10646 Coded Character Set (CCS) with the Character Encoding Scheme (CES) specified in the above document. It covers exactly the UTF-16-reachable subset of ISO 10646. SCSU can also be classified as a Transfer Encoding Syntax (TES), but one specifically designed for Unicode/ISO 10646. ISO 10646 equivalency table: Same as specification. Additional Information: SCSU is an encoding (CES/TES) of Unicode/ISO 10646 that allows significant size reduction of text compared to UCS Transformation formats. It approximates the size of text that is otherwise achieved with language-specific charsets while encoding all of Unicode (up to U-0010ffff). SCSU is byte-based, which helps further, traditional compression (LZW etc.). It is stateful and uses all byte values including NUL. CRLF may or may not be represented by 0x0d 0x0a depending on the encoder and the text. Encoders can be trivial by emitting one command byte (0x0f) followed by the text in UTF-16BE. Fairly simple encoders yield good results with average text of any length. Decoding is simple and requires no mapping tables. If no control characters other than NUL, TAB, CR, and LF are used, then text in US-ASCII or ISO-8859-1 is already valid SCSU text. There is a Unicode signature byte sequence defined (0e fe ff, see specification). SCSU is of no use for applications that require a canonical representation of text. It is not suitable for process-internal use. This is an intentional part of its design. Personal & email address to contact for further information: Markus W. Scherer IBM Java Technology Center 10275 N. DeAnza Blvd Cupertino, CA 95014-2237 markus.scherer@jtcsv.com schererm@us.ibm.com Intended usage: LIMITED USE Thank you for your consideration, markus
Received on Thursday, 15 June 2000 11:47:13 UTC