The granularity of an Observation or Measurement event is somewhat arbitrary; largely dependent on how the measurement results are packaged for consumption. For example, a WMO synoptic observation aggregates data from multiple procedures each of which are considered to be part of an aggregate procedure defined in regulation. The execution of this aggregate procedure is considered to be a single event, and is thus described using a single Observation instance.<br /></p><p><br /></p><p>Thus a single Procedure may evaluate a number of physical properties.<br /></p><p><br /></p><p>Where quantitative properties are evaluated, it is essential that the resolution [1] and measuring interval [2] of the measurement procedure can be specified.<br /></p><p><br /></p><p>The abstract class 'AbstractMeasurementContext' enables either a simple context definition (where a single quantity is evaluated as a result of the procedure) or a complex context definition comprising of 2 or more simple definitions.<br /></p><p><br /></p><p>[1] Resolution: smallest change in a quantity being measured that causes a perceptible change in the corresponding indication (from the 'International vocabulary of metrology' [http://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2008.pdf])<br /></p><p>[2] Measuring interval: set of values of quantities of the same kind that can be measured by a given measuring instrument or measuring system with specified instrumental uncertainty, under defined conditions (from the 'International vocabulary of metrology' [http://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2008.pdf])<br /></p>