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. 34

Section 2.2.7.4.8. Special generic values

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

2.2.7.4.8. Special generic values

| top | pdf |

(21) The unquoted character literals ? (query mark) and . (full point) are special and are valid expressions for any data type.

(22) The value ? means that the actual value of a requested data item is unknown.

(23) The value . means that the actual value of a requested data item is inapplicable. This is most commonly used in a looped list where a data value is required for syntactic integrity.








































to end of page
to top of page