Layout
There are rules concerning the number of tatami mats and the layout of the tatami mats in a room. In the Edo period, "auspicious" tatami arrangements and "inauspicious" tatami arrangements were distinctly differentiated, and the tatami accordingly would be rearranged depending on the occasion. Nowadays, the "auspicious" layout is ordinarily used. In this arrangement, the junctions of the tatami form a "T" shape; in the "inauspicious" arrangement, the tatami are in a grid pattern wherein the junctions form a + shape.
An inauspicious layout is said to bring bad fortune. In homes, the mats must not be laid in a grid pattern, and in any layout there is never a point where the corners of four mats touch.
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