A Boolean operation,as in A OR B, in which the statement is true if either A or B(or both) is true.

A Boolean operation,as in NOT A , that changes the value of statement from true to false or from false to true.

Deriving the location for a record in a random file from the record key.

Checking the value of a field to be sure it is acceptable is editing input by means resticted-value test.

Instructions thet are executed when an error is encountered during processing.