What is the convention for Lisp filename extension?

Question

".el" is the convention for filename ending with Emacs Lisp programs. What is the convention when writing Common Lisp programs, please?

question from:https://stackoverflow.com/questions/15187240/what-is-the-convention-for-lisp-filename-extension

Answer 1

Wikipedia and the Google Common Lisp Style guide both suggest .lisp.

Practical Common Lisp suggests .lisp or .cl.

Note, I'm not a Common Lisp programmer by any measure, so I have no idea if .lisp is actually used in practice.