Language > Variables > System Variables

# System Variables

### General System Variables

!CPU - Controls the state of the IDL thread pool.

!DEBUG_PROCESS_EVENTS - Allow processing of widget events while stopped.

!DIR - Path to the main IDL directory.

!DLM_PATH - List of search paths for DLM files.

!EDIT_INPUT - Controls command-line editing.

!HELP_PATH - List of search paths for HELP files.

!JOURNAL - Contains the LUN for journal output.

!MAKE_DLL - Configure options for MAKE_DLL and CALL_EXTERNAL.

!MORE - Controls pagination for long help output.

!PATH - List of search paths for IDL routines.

!PROMPT - The text string for the prompt.

!QUIET - Print or suppress informational messages.

!VERSION - Information about the running IDL process.

### Constant System Variables

!COLOR - Contains standard RGB color triplets.

!CONST - A list of physical constants.

!DPI - Double-precision value of pi.

!DTOR - Convert degrees to radians.

!FALSE - Boolean value of false (0).

!MAP - Direct Graphics map information.

!NULL - A variable of type Undefined.

!PI - Single-precision value of pi.

!RADEG - Convert radians to degrees.

!TRUE - Boolean value of true (1).

!VALUES - Contains IEEE values for Infinity and NaN.

### Error Handling System Variables

!ERROR_STATE - The state of the last error message.

!EXCEPT - Controls how math exceptions are handled.

!MOUSE - The mouse status from the last cursor read operation.

!WARN - Controls warnings about obsolete routines and use of parentheses.

### Direct Graphics System Variables

!D - State of the Direct Graphics device.

!ORDER - Controls whether Direct Graphics images are ordered top-to-bottom.

!P - State of the Direct Graphics plotting system.

!X - State of the Direct Graphics x-axis

!Y - State of the Direct Graphics y-axis

!Z - State of the Direct Graphics z-axis