In estimating the distance between lines, it should be borne in mind that all typewriters and billing machines are arranged for spacing one line, two lines, and three lines. By adjusting the spacing device, the paper can be advanced the width of one, two, or three lines. All headings on the invoice should be arranged so that the next writing point below, on the invoice or order, will be one, two, or three spaces, and the beginning of the body of the bill should be arranged for in the same manner. This prevents any waste of time, and eliminates the necessity of throwing off the ratchet spacing device of the machine and turning the carriage by hand. The first printing point on an order or billing form should be placed in such a manner that the marginal stop of the typewriter carriage, instead of a tabulator stop, will be available for use. The second writing point on the form should be the first column stop (the column finder on the billing machine is the device which automatically stops the carriage at certain given points). The third writing point on the line should be the second column stop, or decimal tabulator stop, according to the one which is on the machine. In Fig. 21 is shown an illustration showing the top sheets of an order form designed to facilitate the work of the billing machine. In addition to having all of the printed headings aligned vertically on the last letter of each word, each line is either one space or two spaces of the billing machine platen (rubber roll). This eliminates any waste of time in spacing the order form through the machine. [Illustration: Fig. 20. Styles of Typewriter and Billing Machine Type ] The last sheet of the form of the McCaskey Register Co. is cardboard, with the numbers _1_ to _31_ printed along the top. A movable metal "spud," or tip, is used to show the due dates of each invoice, and to enable the collection clerks to quickly find the desired copies of charges for the purpose of sending out statements from three to five days ahead of due dates. =Styles of Type.= The size and style of type is a very important factor in all classes of work where legible manifolding results are wanted. There are several classes of type used in connection with billing machines. Different companies use different names in describing them. The four sizes of type used are as follows: ELITE PICA MEDIUM ROMAN LARGE (or full) ROMAN _Elite._ This style has come into general use in connection with correspondence. It gives a dignified style to a letter. It is the hardest type to keep clean—the most destructive to the rubber roll and typewriter ribbon of any type made. It also manifolds very poorly where a number of copies are used, as the type is so small that the sixth or seventh copy, and many times the third and fourth, are so blurred that it is impossible to tell an _e_ from an _a_ or an _o_.