To purchase a separate copy of the index, see the Index to the U.S. Patent Classification System. Offered as a subscription which consists of the basic manual and supplementary material for an indeterminate period. There are approximately 450 main divisions of technology in the MCF, called classes, which are broken into approximately 150,000 subdivisions, called subclasses. The file is available in two sequences, by patent number with current classification, or by classification with all the patent numbers included in that classification. The MCF is completely updated every two months and contains all patents issued since 1790 with their current classifications.
Price is for an annual subscription.