MNULOAD command is reserved for LISP. Download and install LISP extension module (Homepage->Extension Modules section) and MNULOAD will load lisp routines and toolbars from bcad.mnu configuration file that can be found in .../ProgramFiles(x86)/BabaCAD/BabaCAD/Support. You can also add your .lsp files in ..Support/Lisp folder to be loaded on startup. After that you can type custom lisp commands in BabaCAD command line to execute (see examples in ..Support/Lisp folder).
