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. 2.2, p. 27

Section 2.2.7.1.9. Implementation restrictions

S. R. Hall,a* N. Spadaccini,c I. D. Brown,d H. J. Bernstein,e J. D. Westbrookb and B. McMahonf

2.2.7.1.9. Implementation restrictions

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(27) Certain allowed features of STAR File syntax have been expressly excluded or restricted from the CIF implementation.

2.2.7.1.9.1. Maximum line length and character set

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(28) Lines of text may not exceed 2048 characters in length. This count excludes the character or characters used by the operating system to mark the line termination.

The ASCII characters decimal 11 (VT) and 12 (FF) are excluded from the allowed character set [see paragraph (22)].

2.2.7.1.9.2. Maximum data-name, block-code and frame-code lengths

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(29) Data names may not exceed 75 characters in length.

(30) Data-block codes and save-frame codes may not exceed 75 characters in length (and therefore data-block headers and save-frame headers may not exceed 80 characters in length).

2.2.7.1.9.3. Single-level loop constructs

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(31) Only a single level of looping is permitted.

2.2.7.1.9.4. Non-expansion of save-frame references

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(32) Save frames are permitted in CIFs, but expressly for the purpose of encapsulating data-name definitions within data dictionaries. No reference to these save frames is envisaged, and the save-frame reference code permitted in STAR is not used. This means that unquoted character strings commencing with the $ character may not be interpreted as save-frame codes in CIF. Use of such unquoted character strings is reserved to guard against subsequent relaxation of this constraint.

2.2.7.1.9.5. Exclusion of global_ blocks

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(33) In the full STAR specification, blocks of data headed by the special case-insensitive word global_ are permitted before normal data blocks. They contain data names and associated values which are inherited in subsequent data blocks; the scope of a value extends from its point of declaration in a global block to the end of the file. Because rearrangements of the order of data blocks and concatenation of data blocks from different files are commonplace operations in many CIF applications, and because of the difficulty in properly tracking and implementing values implied by global blocks, use of the global_ feature of STAR is expressly forbidden at this revision. To guard against its future introduction, the special case-insensitive word global_ remains reserved in CIF.








































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