In Symbolics Genera stuff was originally implemented in ZetaLisp with Flavors. Then there is CLtL1, Symbolics Common Lisp (a rather large version of Common Lisp

In Symbolics Genera stuff was originally implemented in ZetaLisp with Flavors. Then there is CLtL1, Symbolics Common Lisp (a rather large version of Common Lisp), ANSI CL, ... There is quite a non-trivial difference between ZetaLisp and Symbolics Common Lisp: both a very large Lisp dialects. ZetaLisp is dynamically scoped, has base 8 integers, the old flavors system is widely used, Fexprs, ... All these Lisp dialects are provided in the same system and one switches the reader/printer and the packages when changing the language: on can set the language context in a listener and also per file.