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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. 2.5, p. 54
Section 2.5.3.1. Example 1: attributes of temperature
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School of Biomedical and Chemical Sciences, University of Western Australia, Crawley, Perth, WA 6009, Australia, and bBCI Ltd, 46 Uppergate Road, Stannington, Sheffield S6 6BX, England |
Every numerical data item has distinct properties. Consider the number 20 as a measure of temperature in degrees. To understand this number it is essential to know its measurement units. If these are degrees Celsius, one knows the item is in the temperature class, degrees Celsius sub-class, and that a lower enumeration boundary of any value can be specified at −273.15. Such a constraint can be used in data validation. More to the point, without any knowledge of both the class and subclass, a numerical value has no meaning. The number 100 is unusable unless one knows what it is a measure of (e.g. temperature or intensity) and, equally, unless one knows what the units are (e.g. degrees Celsius, Kelvin or Fahrenheit; or electrons or volts).
