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.
This calculator determines how much yardage from a bolt of fabric is needed to make a backing for a quilt. It may also be used to determine how much batting you need for your quilt. You specify the width of the fabric on the bolt along with the quilt's width and length.