Usually a flat bed sheet is overlocked around the edges to form four seams. One of the seams is wider than the other three and helps with orienting the sheet correctly on the mattress. The wider seam goes at the head end of the mattress. Sometimes the sides do not have seams, but are finished with the selvedge only. When one makes a bed, the patterned or monogrammed side of the top sheet may be placed facing up, or facing down, in which case the top edge may be folded towards the foot of the bed to expose the design.