LISP, FAS, and Other File Types

The basic file type in VLISP is the AutoLISP source file. Typically, AutoLISP source files are named with an .lsp file extension. You have seen .lsp files used frequently in previous chapters.

The FAS (.fas) file type was introduced in the previous chapter, Building Applications FAS files are compiled AutoLISP files. These files load faster than AutoLISP source files and are more secure because their contents are not intelligible to users.

Here is a brief summary of the types of files used by the VLISP project management feature:

Visual LISP project file types

File ext.

Type of file



Compiled AutoLISP code

Compiled AutoLISP programs. May be loaded and run, or compiled into VLX modules


AutoLISP source code

Program source files


Object code

Used internally by VLISP, these files contain compiled AutoLISP code used in building FAS files


Project database

Used internally by VLISP, these files contain symbol information used by the compiler


Project definition

Contains the location and names of all source files that build the project, as well as certain parameters and rules on how to create the final FAS files

In addition to the files recognized by the project manager, VLISP either creates, processes, or recognizes a number of additional types of files, as summarized below:

Additional Visual LISP file types

File ext.

Type of file



Desktop save

Contains VLISP environment and window settings. (Note: Editing this file may permanently change the VLISP environment. Do not edit this file without creating a backup copy first.)


Backup files

Backup copies of edited files, maintained by the VLISP editor. Backup files contain the same name as the original, except that the file extension begins with the underline character (_) and is followed by the first two characters of the original file's extension. For example, the backup file of a LSP file has an ._LS extension; the backup of a DCL file has a ._DC extension.


Stand-alone applications

Stand-alone AutoCAD applications, which can be created using the VLISP Make Application wizard.

.c, .cpp, .cch, .hpp, .hh

Language source files

Contain program source code. The VLISP editor recognizes the syntax of these files and color-codes reserved words, strings, and numbers.


Dialog control language

Contains definitions of AutoCAD dialog boxes. VLISP can preview these files, and you can include them in Visual LISP executable (VLX) files.


Make application

Defines the files and options used to build a VLX application with the VLISP Make Application wizard.


Structured query language

Contains SQL statements. The VLISP text editor recognizes this file type and color-codes the text according to SQL syntax rules.