= CommonLispObjectSystem (aka. CLOS) = 

The standardized object-oriented extension of CommonLisp. Basics of dynamic class, slot and method 
handling are defined in the MetaObjectProtocol.

See e.g.:
 * [http://en.wikipedia.org/wiki/Common_Lisp_Object_System]
 * [http://www.aiai.ed.ac.uk/~jeff/clos-guide.html]
 * [http://www.lisp.org/table/objects.htm]