1861	 The MAD Definition Facility	 One of the first definition facilities for higher level languages is described. Users of the language can define new operators and or data types into the MAD language so that their use appears as if they were predefined. Information is given on how one writes definitions as well as on much of the motivation behind the form in which definitions are written. Some conclusions are drawn about future definitional facilities. MAD definitions operators macros higher level language
