ICOM stands for Input, Control, Output, Mechanism. They
are the four types of arrows in an IDEF0 Diagram. In more detail, they
Inputs, which are the 'raw material' that
gets transformed during the activity, e.g. a wire coil, outline plans.
Controls, which influence or direct how the
process works, e.g. safety standards, customer requirements, project
Mechanisms, which cause the process to
operate, e.g. people, tools, machines.
Outputs, which are the result of the
activity and are transmitted to other processes, e.g. cut lengths of
wire, final plans.