MNL file
A LISP file with the same base name as a CUIX/CUI menu, loaded automatically when that menu loads.
An MNL (Menu LISP) file shares its base name with an AutoCAD menu file — load mytools.cuix and AutoCAD automatically loads mytools.mnl from the same folder. This is how commercial menus ship the LISP code their toolbar buttons depend on. MNLs run after the menu loads, which means S::STARTUP defined in an MNL also runs once per drawing.
Related terms
AutoCAD's customization file — a zipped XML bundle of menus, ribbon tabs, toolbars, keyboard shortcuts, and the LISP/MNL files they reference.
The AutoCAD command that opens the Customize User Interface editor, where you edit menus, ribbon, and shortcuts.
Autodesk's dialect of LISP, built into AutoCAD since 1986, used to write custom commands and automate drawings.
A LISP file AutoCAD loads every time a drawing is opened, used for per-document setup and (defun S::STARTUP).