XYZ system is a CASE tool system. Its kernel is a temporal logic languageXYZ/E which has a basic lower levels state-transition form XYZ/BE (or XYZ/CE forconcurrency) and a structured higher level form XYZ/SE. Each of them has a corresponding graphic representation. XYZ/CFC and XYZ/PAD are two interactive graphic environments to support programming with stepwise decomposition methodology by means ofXYZ/BE (or XYZ/CE) and XYZ/SE respectively. The Temporal logic form programs canbe generated automatically from the graphic programs at each step.