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

International Tables for Crystallography (2006). Vol. G, ch. 2.1, pp. 15-16

Section 2.1.3.7. Data block

S. R. Halla* and N. Spadaccinib

aSchool of Biomedical and Chemical Sciences, University of Western Australia, Crawley, Perth, WA 6009, Australia, and bSchool of Computer Science and Software Engineering, University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
Correspondence e-mail:  syd@crystal.uwa.edu.au

2.1.3.7. Data block

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A data block is a set of data containing any number of unique items and save frames. A data block begins with a data_blockcode statement, where blockcode is a unique identifying name within a file. A data block is closed by another data_blockcode statement, a global_ statement or an end of file.

Example: [Scheme scheme11]

all information relevant to rhinovirus included here

[Scheme scheme12]

all information relevant to influenza virus
included here

A data block has the following attributes:

  • (a) A block code must be unique within the file containing the data block.

  • (b) Data blocks may not be referenced from within a file [in contrast to save frames – see Section 2.1.3.6[link](d)].

  • (c) The scope of data specified in a data block is the data block. The value of a data item is always associated with the data block in which it is specified.

  • (d) Data specifications in a data block are unique, except they may be repeated within a save frame. Data specifications in a save frame are independent of the parent data block specifications.

  • (e) If a data item is not specified in a given data block, the global value is assumed. If a global value is not specified, the value is unknown.








































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