A kind of secondary reference object. Provides a means, often determined by invariant aspects of the physical environment, of furnishing the primary reference object with axial properties. This in turn facilitates location of the figure. This is achieved by virtue of a reference object which encompasses the primary reference object thus providing an absolute 'field' of reference.

For instance, in the sentence: Big Ben is south of the river Thames, Big Ben is the figure, the entity we are attempting to locate, and the river Thames is the primary reference object. However, in order to locate Big Ben and establish which side of the river the figure is to be found a secondary reference object is invoked.

In this case, the term south invokes the planet Earth as secondary reference object. It is because this particular reference object, the Earth, encompasses the primary reference object that it is referred to as encompassing.