This class provides a simple parameter, start_date, end_date, count summary of a single phenomenon, maximising the information available for a single parameter A container class for summary of sampling at a site This object contains a specialised dictionary of parameterised Phenenomen Definitions, supporting grouping, as well as a set of well-known aggregation levels. A view of the sampling feature with some subset of the constrained observations, where the result set is a trend over the sampled time envelope. This object is a container for simple (scalar) characterisations of the state of a feature at a sampling site. The business purpose is to allow simple queries to select sites of interest, or to symbolise sites accordingly. Many different characterisations are possible. This class is abstract, and should be extended for specific cases.