of the needle bar threading instructions can be specified in a variety of ways one way is to diagrammatically represent the filled guiders as a 34 1 34 and the empty guiders as a 34 34 but apart from the 34 full set 34 which means obviously all guiders threaded and 34 half set 34 which means alternate guiders threaded the usual instruction is given in the form 34 1 in 2 out 34 or 34 2 in 2 out 34 and so on clearly a computer can be programmed to 34 understand 34 any of these instructions fig3 shows a lapping instruction that would ordinarily be regarded as prohibited notated 0 2 2 0 and repeat it forms or attempts to form an overlap over two needles ordinarily this causes high tensions which can damage the yarns and bend or break the knitting elements the reason for this is that both needles attempt to form stitches and consume even if only temporarily comparatively long lengths of yarn in the loop formation occasionally this is permitted but ordinarily fabrics do not use this kind of construction and the computer may be programmed to prevent operation of the machine if such a construction is inadvertently instructed fig4 shows a three.