Microfilm finding-keys: Dual dictionary

The display of a Dual Dictionary on microfilm is compact and easy to use. Each frame includes the name of a descriptor and 10 columns of numbers representing the documents to which the descriptors were applied. The numbers are assigned to the columns on the basis of the value of the unit digit. Kodamatic indexer lines may be included. A set of computer programs has been written to produce a Dual Dictionary on microfilm. The index is readily updated and replicated. Furthermore, the program accommodates a dictionary or document collection of any size. Dual‐Dictionary displays have been generated for a chemical fragment index, including 70,000 compounds averaging 5 fragments per compound, and for several smaller collections of reports and other data.