College rule (also known as medium ruled paper) is the most common lined paper in use in the United States. It is generally used in middle school through to college and is also popular with adults.The horizontal spacing is 9/32" or 7.1mm. Trim sizes with a width over 6" include a margin ruled 1 1⁄4 inches (32 mm) from the left hand of the page. Smaller trim sizes do not include a margin.This is a good choice for teen or adult notebooks and composition books (known as exercise books outside the US).