illustrated in fig3 the introduction of vacuum pressure between the windows and the duct is controlled by a plurality of plunger shutters 68 68 which are used to individually close and seal each window associated with the respective zone and are connected to the table for this purpose to pneumatic or electrical actuators 44 44 to move the shutters between closed and open positions the windows are generally elongate openings extending in their lengthwise direction parallel to the indicated x coordinate direction of the table the windows in essence define the width w of a plurality of zones z 1 z 2 z 3 z 4 z 5 having shorts sides extending parallel to the length dimension of the table and along sides extending parallel to the width dimension of the table thus for a table on the order of 6 feet long five separate vacuum zones are provided each being approximately 14 inches in length this dimension only being mentioned for purposes of illustration and should not be construed as limiting since different configurations for zones can be adapted by applicable software for example to accommodate a greater number of zones each having a narrower dimension for a more complete description of the vacuum system in the illustrated example reference may be had to the aforementioned pearl et al u s pat no 4 730.