2011

1 If the input is a null response (SPACEBAR or ENTER), AutoCAD uses the
name of the last command issued. HELP is the default.
2 AutoCAD checks the command name against the list of built-in
commands. If the command is in the list and is not preceded by a period
(.), AutoCAD then checks the command against a list of undefined
commands. If the command is undefined, the search continues.
Otherwise, the command is run, unless another reason prevents it from
doing so. Running it transparently or in Perspective mode might be
impossible.
3 AutoCAD checks the command name against the names of commands
defined by a device driver, and then by those defined by the display
driver.
4 AutoCAD checks the command name against the external commands
defined in the program parameters file (acad.pgp). If the command name
corresponds to a defined external command, that command runs, and
the search is complete.
5 AutoCAD checks the command name against the list of commands
defined by AutoLISP or ObjectARX applications. At this point, an
autoloaded command is loaded.
6 AutoCAD checks the command name against the list of system variables.
If the command name is in the list, AutoCAD executes the SETVAR
command, using the input as the variable name.
7 If the command name corresponds to a command alias defined in the
program parameters file, AutoCAD uses the expanded command name
and continues the search, starting a new search against the list of built-in
commands.
8 If all the preceding steps fail, the search terminates with a warning
message about illegal command names.
See also:
■
Overview of AutoLISP Automatic Loading on page 440
■ “Specify Search Paths and File Locations” in the User's Guide
6 | Chapter 1 Basic Customization