||AttributDefinition is used to define the formal parameters of external functions and the underlying
rendering operations of the portrayal service.
||The AttributValue holds the value for an associated AttributeDefinition.
External functions are used to perform computations that sometimes are needed to evaluate the query
statements and/or perform the portrayal rules.
||A parameter set holds a list of actualparameter values.
||A portrayal operation holds the details for a particular portrayal operation.
||A portrayal service is used to portray a feature instance or instances.