Abstract: A data transmission network congestion control mechanism requires knowledge of the sequence of occurrence of two dates d1 and d2, respectively defined by times t1 and t2 provided by a wraparound timer as respective numbers A and B coded in a 2's-complement form. Relative date discrimination is implemented by dividing the wraparound timer period into four consecutive intervals, each defined by the two most significant bits of the timer count. The value of the most significant bits and the sign of A-B, are used to derive a one-bit "X" indicator, the binary value of which indicates which of the two dates d1 and d2 was first to occur.

Abstract: The invention concerns a folding door of the kind having a primary panel pivoted about one axis on a frame, and a secondary panel articulated with respect to the primary panel and engaging a slide guide which is perpendicular to the pivotal axis of the primary panel.According to the invention, the two panels are articulated by links pivotally connected to each of the primary and secondary panels at second and third axes respectively, and the secondary panel engages the slide guide at a fourth axis located at an intermediate point along the panel, all the four axes being disposed centrally of the thickness of the panels; furthermore, the distance between the second and third axes is equal to the thickness of the panels, and the distance between the third and fourth axes is the same as between the first and second axes.With this construction, the door will open in a substantially smaller space than a conventional door and in addition it can be opened by a simple pushing action.