Tables for
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G. ch. 2.3, p. 40

Section Details of the magic number

H. J. Bernsteina* and A. P. Hammersleyb

aDepartment of Mathematics and Computer Science, Kramer Science Center, Dowling College, Idle Hour Blvd, Oakdale, NY 11769, USA, and bESRF/EMBL Grenoble, 6 rue Jules Horowitz, France
Correspondence e-mail: Details of the magic number

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The magic number identifier is ###CBF: VERSION. This must always be present so that a program can easily identify a CBF by simply inputting the first 15 characters. [The space is a blank (ASCII 32) and not a tab. All identifier characters must be upper case.] The first hash means that this line within the CIF is a comment line. Three hashes mean that this is a line describing the binary file layout for CBF. (All CBF internal identifiers start with three hashes, and all others must immediately follow a `line separator'.) No white space may precede the first hash sign. Following the file identifier is the version number of the file; e.g. the full line might appear as ###CBF: VERSION 1.0. The version number must be separated from the file identifier characters by white space, e.g. a blank (ASCII 32). The version number is defined as a major version number and minor version number separated by a decimal point. A change in the major version may mean that a program for the previous version cannot input the new version as some major change has occurred to CBF. A change in the minor version may also mean incompatibility if the CBF has been written using some new feature. For example, a new form of linearity scaling may be specified; this would be considered a minor version change. A file with the new feature would not be readable by a program supporting only an older version of the format.

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