CLIM presentation types are designed to use inheritance, just as CLOS classes do. For example, a university might need to model "night-student," which is a subclass of "student." When the input context is looking for a student, night-students are sensitive because they are represented as a subtype of student.
The set of presentation types forms a type lattice, an extension of the Common Lisp CLOS type lattice. When a new presentation type is defined as a subtype of another presentation type, it inherits all the attributes of the supertype except those explicitly overridden in the definition.
Common Lisp Interface Manager 2.0 User's Guide - 3 Mar 2015