PURPOSE: To set a boundary point which can be controlled and observed between two domains with comparatively few hardware condition.

CONSTITUTION: The inter-domain latch for setting the boundary point which can be controlled and observed between the two domains in successive logic design having the two domains having opposite edge clocks for a flip flop is constituted of three multiplexers and three latches. A first multiplexer 42a and a first latch 52a, a second multiplexer 44a and a second latch 4a, a third latch 56a and a third multiplexer 46a are connected in series. The output of the first latch 52a bypassed to the third multiplexer 46a.