VLX

Short answer

A compiled Visual LISP application that bundles multiple .lsp/.fas files, DCL dialogs, and resources into one file.

A .vlx is a Visual LISP eXecutable — a single file that bundles compiled LISP modules, DCL dialog files, and supporting resources into one deliverable. VLX is the standard shipping format for larger commercial LISP applications because the buyer only has to drop one file in the support path. Internally a VLX is just a sealed archive of compiled FAS plus a manifest, and it's loaded the same way as any other LISP file.

Related guides

How to Load a LISP Routine in AutoCAD

Three reliable ways to load .lsp, .fas, and .vlx files into AutoCAD, plus how to add them to the Startup Suite so you never reload again.

Related terms

FAS

A compiled, single-file binary of an AutoLISP/Visual LISP routine. Faster to load and obscures the source code.

Visual LISP

An extended LISP environment in AutoCAD that adds an IDE, debugger, COM access, and the ability to compile to FAS or VLX.

DCL

Dialog Control Language — a small markup AutoCAD uses to define LISP dialog boxes.