The ASSIGNED function returns a Boolean TRUE or FALSE result depending on whether or not a variable has been assigned a value.
ASSIGNED returns TRUE if the variable named has been assigned a value before the execution of this statement. If the variable has never been assigned a value then the function returns FALSE.
This function has been provided for compatibility purposes, as it has been implemented in older implementations of the language. It is far better to program in such a way that this statement will not be needed.
See also UNASSIGNED.