-- Name --<br /></p><p>Constraint<br /></p><p>-- Definition --<br /></p><p>A constraint on some property e.g. wavelength = 200nm.<br /></p><p>-- Description --<br /></p><p>A constraint on some property e.g. wavelength = 200nm. This property is  typically not the same property as the base phenomenon of the observed property. e.g. <br /></p><p>the observed property has a base phenomenon 'radiance'. <br /></p><p>a constraint is added to say 'wavelength = 200nm'<br /></p><p>So the overall ObservableProperty which is represented is 'radiance where wavelength = 200nm'<br /></p><p>The Constraint class is specialised into several specific classes covering Scalar, Range and Categorical constraints<br /></p>