2.4.8 Dimensions and extent
The best possible information is to be given on stratigraphical thickness, tectonostratigraphical thickness, vertical, horizontal and lateral extent, and the spatial relationships with adjoining geological units. This also applies to non-exposed, subsurface units, such as units on the continental shelf. (N.B. It is not necessary for the complete extent of the unit to be known before it can be formally defined.)