It models the dimension or attribute or primary measure or time value for which data is requested.
The value of the component is accompanied by the operator to apply to the string value.
It is a representation of a SOAP DataQuery 2.1
It represents a single component (dimension or attribute),
with one or more code selections for it along with an operator.
A DataQuerySelectionGroup contains a set of DataQuerySelections which are implicitly ANDED together.