System Variables

System variables retain information used by the system in some way. Many system variables affect the behaviour of primitive functions and operators to which they act as implicit arguments For further information, see System Settings.

System variables may be localised by inclusion in the header line of a defined function or in the argument list of the system function ⎕SHADOW. When a system variable is localised, it retains its previous value until it is assigned a new one. This feature is known as "pass-through localisation". The exception to this rule is ⎕TRAP.

A system variable can never be undefined. Default values are assigned to all system variables in a clear workspace.

Name	Description	Scope
`⎕AVU`	Atomic Vector – Unicode	Namespace
`⎕CT`	Comparison Tolerance	Namespace
`⎕DCT`	Decimal Comp Tolerance	Namespace
`⎕DIV`	Division Method	Namespace
`⎕FR`	Floating-Point Representation	Namespace
`⎕IO`	Index Origin	Namespace
`⎕LX`	Latent Expression	Workspace
`⎕ML`	Migration Level	Namespace
`⎕PATH`	Search Path	Session
`⎕PP`	Print Precision	Namespace
`⎕PW`	Print Width	Session
`⎕RL`	Random Link	Namespace
`⎕RTL`	Response Time Limit	Namespace
`⎕SM`	Screen Map	Workspace
`⎕TNAME`	Thread Name	Workspace
`⎕TRAP`	Event Trap	Workspace
`⎕USING`	Microsoft .NET Search Path	Namespace
`⎕WSID`	Workspace ID	Workspace
`⎕WX`	Window Expose	Namespace

In other words, ⎕PATH and ⎕PW relate to the session. ⎕LX, ⎕SM, ⎕TRAP, and ⎕WSID relate to the active workspace. All the other system variables relate to the current namespace.

Session	Workspace	Namespace
`⎕PATH`	`⎕LX`	`⎕AVU`
`⎕PW`	`⎕SM`	`⎕CT`
	`⎕TRAP`	`⎕DCT`
	`⎕WSID`	`⎕DIV`
		`⎕FR`
		`⎕IO`
		`⎕ML`
		`⎕PP`
		`⎕RL`
		`⎕RTL`
		`⎕USING`
		`⎕WX`

Note that the value assigned to a system variable must be appropriate; otherwise an error will be reported immediately.

Example

      ⎕IO←3
DOMAIN ERROR
      ⎕IO←3
      ^