A screenshot of a portion of the reference manual of the Interlisp programming language. The portion contains the following paragraph of text (emphasis is in the original):
There have been similar efforts in other LISP systems, most notably the MLISP language at Stanford. CLISP differs from these in that it does not attempt to _replace_ the LISP syntax so much as to _augment_ it. In fact, one of the principal criteria in the design of CLISP was that users be able to freely intermix LISP and CLISP without having to identify which is which. Users can write programs, or type in expressions for evaluation, in LISP, CLISP, or a mixture of both. In this way, users do not have to learn a whole new language and syntax in order to be able to use selected facilities of CLISP when and where they find them useful.