Suppose, for example, that correspondence develops with B. J. Anderson. We will file his letter or a copy of our reply in the next unused numbered folder--which happens to be _No. 545_--and this will be Mr. Anderson's number as long as we have any dealings with him. Before placing the folder in the proper place in the file--following folder _No. 544_, back of guide _540_--we will write Mr. Anderson's name near the upper edge, and at the same time we will fill out an index card as shown in Fig. 15. This card will be filed in its proper place in the card index drawer, and whenever we wish to refer to this correspondence we will turn to the card, which shows that it will be found in folder _No. 545_. When a letter refers to more than one person or subject, it is filed under the most important. For example, when correspondence develops with a firm, it should always be filed under the firm name, even though the letters are signed by individuals. We will suppose that one of our correspondents is the Norton Machine Co., and that folder _No. 610_ is assigned. Later, a letter signed by T. J. Watson, Secretary, is received. Since the letter refers to the business of the Norton Machine Co., it will be filed in their folder, and we will fill out a cross-index card for T. J. Watson, Secretary, referring to the company's folder, as shown in Fig. 16. This will be filed with the other cards in the alphabetical card index, and will enable us to locate the correspondence of T. J. Watson, even if we do not remember the name of the company. [Illustration: Fig. 15. Index Card for Numerical Filing] _Alphabetical Indexing._ The alphabetical is the simplest method of indexing. The guide or index cards are printed with the letters of the alphabet, providing an alphabetical index between which the folders are filed. Sets of alphabetical guides with any number of subdivisions up to 4000 are to be had. [Illustration: Fig. 16. Indexing Firm Correspondence for Numerical Filing] With the alphabetical system a folder is assigned to each regular correspondent, as with the numerical system, but instead of a number, only the name is written on the folder, or on the tab projection. The folder is filed back of the proper alphabetical guide, as in Fig. 17, and is used exclusively for that one correspondent. [Illustration: Fig. 17. File with 50 Alphabetical Subdivisions _Browne-Morse Co._] It is the experience of every business house that a small correspondence is received from a large number of persons. Perhaps but one or two letters will be received, the person never developing into a regular correspondent. This correspondence is treated as miscellaneous. For miscellaneous correspondence a separate folder, on which the index letters are written or printed, is used for each alphabetical subdivision. This may be placed either behind or in front of the name folders, as in Fig. 18.