Coordinate indexing, a system invented by Dr. Mortimer Tauhe and his associates in Documentation incorporated, is based on the conception of the uniterm. The theory is that each book or periodical title, each periodical article, etc., can be reduced for indexing purposes to a number of basic ideas capable of being represented mostly by single terms. In the uniterm system each book, document, or other item is numbered as it is received and, if a record is kept of the number registered each day or week, it is possible to gain an approximate idea of such receipts each day or week. It is also possible to gain an approximate idea of the date of any currently published item from its serial number. The title, salient contents, etc., of the document to be indexed are then analysed into fundamental terms usually of one word each. These constitute the uniterms and a separate card entry is made for each uniterm. Each card allows for sufficient space in the vertically ruled ten columns representing the numbers 0 to 9. The serial numbers of relevant documents are entered in the column of appropriate uniterm cards according to the last digit—the purpose of the columns being merely to break up the numbers on the cards into roughly ten equal groups, which not only makes the utmost use of available space but also helps to accelerate the finding of document. Thus, a title called Uniformity in Groups could be indexed under the uniterms mechanisms, pressures, uniformity and groups. Serial numbers common to two or more cards indicate documents relevant to the subject and scrutiny of the document themselves will finally identify the one required. Thus, if four salient terms are remembered correctly, it is probable that the exact document will be discovered immediately, no matter in what order those terms are recalled.