=Carbon Paper Cut for this Class of Work.= Some operators doing condensed billing work prefer to use carbon paper the same size as the invoice, and to remove the carbon paper each time an invoice is completed. This necessitates a great deal of handling of carbon paper. It is preferable to use a large sheet of carbon paper the same size as the sales sheet, feeding it through the billing machine with the sales sheets. This eliminates the necessity of picking up a piece of carbon paper each time an invoice is placed in the machine. With the former method, if one had four invoices to one page of a sales sheet, it required one to pick up the same piece of carbon paper four times, or once with each invoice. The latter plan necessitates handling the carbon paper once only, when the sales sheet is placed in the machine. The operator positions the second or third invoice on a sales sheet, in order to avoid writing over the previous invoice, by spacing the carriage three times after an invoice is completed. =Using the Sheets Serially.= All sales sheets should be serially numbered, in order that when placed in a binder the loss of any sheet may be detected by a missing number. Some firms prefer to use one side of a sales sheet only. In this case, a sales binder holding 375 sheets would have 375 pages. Where the sheets are numbered on both sides, the sales binder would have 750 pages. If the appearance of a page is marred by an invoice being spoiled, that sheet is not thrown away, and the fact that it is not is an incentive for the operator to do good work. =Handling Credit Memoranda.= Some firms prefer to handle their credit memoranda on different-colored paper (generally pink) for both invoices and the large sheets which correspond to sales sheets. All of the rules which govern the making of invoices and loose-leaf sales sheets apply to the execution of credit memoranda. =General Remarks Regarding Billing Machines.= The flat-bed billing machine enlarged somewhat upon the idea of using special characters for certain abbreviations peculiar to various lines of trade. For instance, in the shoe business, the following abbreviations are some of those used: WOM means Women's CHI " Child's BOYS' " Boys' BAL " Balmorals BLU " Bluchers PR " Pair PRS " Pairs DOZ " Dozens