used wall-to-wall, entirely covering the floorboards. Tatami dimensions were regionally standardized, and the other elements of the room became proportioned to the mats; standardization of building components reduced waste and the need for custom fabrication, and thus cost (standard lumber, for instance, came in exactly the dimensions needed by the carpenter). Lower-class buildings adopted some of the cheaper elements of the Shoin style, where the law permitted it (class-based limitations were not lifted until the Meiji Era, in the late 1800s). Minka (commoner's houses) rarely used sliding mountings at this time, and generally had only small windows. A variety of specialized hiki-do were developed (along with intermediate forms). Apart from shoji, there were fusuma, similar but with opaque paper, and maira-do, plank-and-batten wooden doors (). Maira-do replaced shitomi-do as rain-protection doors. Initially, the beams between the outer support posts were cut with three grooves; the innermost one for the shoji, and the outer two for mairado-do. This meant that the hashira-ma was generally at least half-obscured, although the other half could be open, shoji-filled, or closed. In the first half of the 1600s, at the beginning of the Edo period, the outermost groove was moved outside the line of pillars. The wooden shutters placed in this groove interlocked edge-to-edge, and were called ama-do (, "rain-door"): they were storm shutters, used only at night and in poor weather. To open the building in the morning, each ama-do would be slid along (rotating at corners) to the end of groove, where they were stacked in a box called a to-bukuro (, : literally, "door-container"). The to-bukuro might be designed to swing out of the way. The inner two grooves remained as they were, but both could now be filled with shoji, doubling the number of shoji in a building. Lightweight shoji could be lifted out and carried away easily. This new structure allowed the entire side of the building to be opened, giving either twice as much light, from an uninterrupted wall of shoji, or an unobstructed view of the garden; gardens changed accordingly. By the mid-1600s, single-track ama-do had spread, and the ama-do might be placed on the outside of the engawa. The combination of architectural changes marked the end of the shoin style, and the beginning of the sukiya style. Unlike the Shiden and Shoin styles, the Sukiya system was, and still is, used in Japanese buildings of all classes.