Maybe you were looking for one of these abbreviations: RCMX-RCN-RCNC-RCNN-RCNO-RCO-AK-RCO-NE-RCoA-RCOCI-RCOE.
Measure the width of your quilt and add 4-6 (or chosen excess). Design a backing to equal that width, adding 1/2 to each panel for each seam you'll use to sew it to a neighboring panel. Cut panels to the length of your quilt plus 4-6 (or chosen excess). Sew panels together with a 1/2 seam allowance. Press seams open to reduce bulk. Press backing before use.
The amount of yardage needed is rounded up to the nearest eighth of a yard. For example, suppose the backing you need for a quilt is 52 inches wide by 96 inches long and the fabric you wish to use for the backing is on a bolt of fabric whose width is 43 inches. The yardage required is 5 1/3 yards. Here, the seam runs in the direction of the 96 inch side.