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[Cif2-encoding] Revised Motion
- To: Group for discussing encoding and content validation schemes for CIF2 <cif2-encoding@xxxxxxxx>
- Subject: [Cif2-encoding] Revised Motion
- From: "Herbert J. Bernstein" <yaya@xxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 30 Sep 2010 09:40:21 -0400
- In-Reply-To: <a06240802c8ca32fa3108@[192.168.2.104]>
- References: <alpine.BSF.2.00.1009271801070.86201@epsilon.pair.com><alpine.BSF.2.00.1009271900080.86201@epsilon.pair.com><AANLkTikudiXBk7orHSAH=JonoeQHeNXVrzvAZmH3Wt94@mail.gmail.com><646265.82162.qm@web87004.mail.ird.yahoo.com><8F77913624F7524AACD2A92EAF3BFA5416659DEDE7@SJMEMXMBS11.stjude.sjcrh.local> <alpine.BSF.2.00.1009281501030.93180@epsilon.pair.com><8F77913624F7524AACD2A92EAF3BFA5416659DEDE9@SJMEMXMBS11.stjude.sjcrh.local> <a06240801c8c840b90dc7@[192.168.2.104]><20100929102536.GB24670@emerald.iucr.org><alpine.BSF.2.00.1009291001300.12237@epsilon.pair.com><20100930084028.GC9485@emerald.iucr.org><alpine.BSF.2.00.1009300540110.389@epsilon.pair.com><629785.55688.qm@web87004.mail.ird.yahoo.com><a06240802c8ca32fa3108@[192.168.2.104]>
Dear Colleagues, James and I had a good e-meeting and came up with the following revised wording. If anybody objects to this motion, please speak up now. We intend to bring this to the DDLm group and then COMCIFS and add annexes on particular encoding-disambiguation algorithms and signature later. Regards, Herbert =============================================================== Proposed position on CIF2 character encodings submitted to COMCIFS for a vote as an interim agreement on what can be agreed thus far, subject to extension and refinement in the future. =============================================================== Reference to character(s) means abstract characters assigned code points by Unicode. Specific characters are referenced according to Unicode convention, U+xxxx[x[x]], where xxxx[x[x]] is the four- to six-digit hexadecimal representation of the assigned code point. The designated character encoding for CIF2 is UTF-8 as the preferred concrete representation of the information in a CIF2 document. Reference to ASCII characters means characters U+0000 through U+007F, or, equivalently the first 128 characters of the ISO-8859-1 (LATIN-1) character set. Reference to newline or \n means the sequence that conventionally terminates a line record (which is environment dependent). Reference to whitespace means the characters ASCII space (U+0020), ASCII horizontal tab (U+0009) and the newline characters. Without regard to local convention, the various other characters that Unicode classifies as whitespace (character categories Zs and Zp) do not constitute whitespace for the purposes of CIF2. CIF2 files are standard variable length text files, which for compatibility with older processing systems will have a maximum line length of 2048 characters. As discussed above and below, however, there are some restrictions on the character set for token delimiters, separators and data names. References to Unicode and UTF-8 are specifically to identify characters and a concrete representation of those characters in an established and widely available standard. It is understood that CIF2 documents may be constructed and maintained on computers that implement other character encodings. However, for maximum portability only the clearly identified equivalents to the Unicode characters identified above and below should be used and use of UTF-8 for a concrete representation is highly recommended. If a CIF2 file contains characters equivalent to Unicode code points greater than U+0076 (126 decimal), then the particular encoding used must be either be UTF8 or algorithmically identifiable from the CIF2 file itself. UTF16 with a BOM conforms to this requirement. The use of a BOM for unicode encodings including UTF8 is recommended. Acceptable identification algorithms will be published as necessary as annexes to this standard (see discussion of magic code and encoding-disambiguation below). A CIF2 file is uniquely identified by a required magic code at the beginning of its first line. The code is #\#CIF_2.0 followed immediately by whitespace. The immediately following space on this is reserved for encoding-disambiguation signatures (see above). If there is a BOM the magic code should follow the BOM. In keeping with XML restrictions we allow the characters U+0009 U+000A U+000D U+0020 -- U+007E U+00A0 -- U+D7FF U+E000 -- U+FDCF U+FDF0 -- U+FFFD U+10000 -- U+10FFFD In addition, character U+FEFF and characters U+xFFFE or U+xFFFF where x is any hexadecimal digit are disallowed. Unicode reserves the code points E000 - F8FF for private use. The IUCr and only the IUCr may specify what characters are assigned to these code points in the context of CIF2. CIF2 processors are required to treat <U+000A>, <U+000D> and <U+000D><U+000A> as newline characters, by normalising them to <U+000A> on read. No other characters or character sequences may represent newline. In particular, CIF2 processors should not interpret the Unicode characters U+2028 (line separator) or U+2029 (paragraph separator) as newline. -- ===================================================== Herbert J. Bernstein, Professor of Computer Science Dowling College, Kramer Science Center, KSC 121 Idle Hour Blvd, Oakdale, NY, 11769 +1-631-244-3035 yaya@dowling.edu ===================================================== _______________________________________________ cif2-encoding mailing list cif2-encoding@iucr.org http://scripts.iucr.org/mailman/listinfo/cif2-encoding
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- Re: [Cif2-encoding] Revised Motion (SIMON WESTRIP)
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- References:
- Re: [Cif2-encoding] How we wrap this up (Herbert J. Bernstein)
- Re: [Cif2-encoding] How we wrap this up (Herbert J. Bernstein)
- Re: [Cif2-encoding] How we wrap this up (James Hester)
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- [Cif2-encoding] Skype conference call 8:45 am EDT,Thursday 30 September 2010 (Herbert J. Bernstein)
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