International
Tables for Crystallography Volume G Definition and exchange of crystallographic data Edited by S. R. Hall and B. McMahon © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. G. ch. 2.2, p. 22
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The characters permitted in a CIF are in effect the printable characters in the ASCII character set. However, a CIF may also be constructed and manipulated using alternative single-character byte mappings such as EBCDIC, and multi-byte or wide character encodings such as Unicode, provided there is a direct mapping to the permitted ASCII characters. Accented characters, characters in non-Latin alphabets and mathematical or special typographic symbols may not appear as single characters in a CIF, even if a host OS permits such representations.
White space (used to separate CIF tokens and within comments or quoted character-string values) is most portably represented by the printable space character (decimal value 32 in the ASCII character set). In an ASCII environment, white space may also be indicated by the control characters denoted HT (horizontal tab, ASCII decimal 9), LF (line feed, ASCII decimal 10) and CR (carriage return, ASCII decimal 13). To ease problems of translation between character encodings, the characters VT (vertical tab, ASCII decimal 11) and FF (form feed, ASCII decimal 12) are explicitly excluded from the CIF character set; this is a restriction that is not in the general STAR File specification (Chapter 2.1
).