The A rule shows Standard Inches in increments of 64ths of an inch photographically printed along its top edge. It has numbers every 32nd of an inch, every 16th, every 8th and so on— for the entire length of the rule. Metric Millimeters & Centimeters, in half-mm markings, are printed along the 30 cm bottom edge. In scientific circles, mm and cm are referred to as metric measurements or SI units (from the French Systéme Internationale). To round out this classic Schaedler Rule, we have placed Printers Points & Picas down the center. These are the original points & picas still used in the printing industry — where six picas are equal to .99576 of an inch, not quite a whole inch. This entire Single A rule is coated with a blue color tinge so it will be easier to find on a cluttered work-table. The B Scale has the Decimal Inch divided into 100ths instead of 64ths. Suppose you had to break an 8½ inch page into three equal columns. The easiest way is to divide 8½ by three. The answer is 2.83. But thats a decimal answer. How do you convert it back to standard inches? With the Schaedler Decimal-Inch Rule you won’t have to bother. DTP Points & Picas (DTP = DeskTop Publishing) have been placed on the other edge of this rule. And this time, the points and picas do correspond to standard inches. 12 points = 1 pica; 6 picas = 1 inch. The scale is cumulatively marked in both points and picas for the entire length of the rule (72 picas or 864 points = 12 inches). There is also an Agate Line scale that runs down the center space of this rule. Agate lines were once used to define newspaper advertising space (so many agates by so many columns). Maybe they still are. The B rule has a pinkish cast to help distinguish it from the A rule at a glance.