1. summary Defined() Special function.

Defined()

This [SpecialFunctions special function] has two forms.

In regular source code

function Defined( any_expression ) : Boolean;

Indicates if the value of the expression is defined, depending on execution context it could mean "empty" or "undefined", if such a value exists and is distinct from nil/null.

In a conditional directive expression

function Defined( string_value ) : Boolean;

Indicates if the conditional whose name is specified by the string is defined.

This function is also available in source code a [SpecialConditionalDefined ConditionalDefined()].