AutoLISP Developer's Guide > Using the AutoLISP Language >  AutoLISP Basics > AutoLISP Variables > 
Predefined Variables
 
 
 

The following predefined variables are commonly used in AutoLISP applications:

PAUSE

Defined as a string consisting of a double backslash (\\) character. This variable is used with the command function to pause for user input.

PI

Defined as the constant p (pi). It evaluates to approximately 3.14159.

T

Defined as the constant T. This is used as a non-nil value.

NoteYou can change the value of these variables with the setq function. However, other applications might rely on their values being consistent; therefore, it is recommended that you do not modify these variables. Visual LISP, by default, protects these variables from redefinition. You can override this protection through the VLISP Symbol Service feature or by setting a VLISP environment option.