Variables Defining Constants

The following variables have fixed values that cannot be changed, i.e., are constant. These variables are the only ones permitted in a CASE statement WHEN command.

$FALSE

False logical value Type: Logical, Read-only

This variable stores the logical constant representing false.

$NULL

“Not Used”, “Not Available” value Type: Null, Read-only

This variable has a special fixed value, which is used to indicate not used or not available. $NULL has a value with a null data type: it is not a number, string, minor word or sequence. $NULL is therefore not equal to any number, string, minor word or sequence.

$P variables and some macro system variables will be set to $NULL to indicate that a value is not available or has yet to be specified.

$PI	PI Trigonometric value Type: Numeric, Read-only

This variable stores the PI trigonometric constant.

$TRUE

True logical value Type: Logical, Read-only

This variable stores the logical constant representing true.