Library of Congress Classification (LCC)
The Library of Congress Classification (LCC) was originally developed by Herbert Putnam with the advice of Charles Ammi Cutter in 1897 for the Library of Congress. It was influenced by the Cutter Expansive Classification and DDC [link to DDC page] and replaced a fixed location system. It has been criticized as lacking a sound theoretical basis, as many decisions were made with respect to the practical needs of the Library of Congress. Although it divides subjects into broad categories it is essentially enumerative in nature.
The main classes are:
Letter classes I, O, W, X and Y are not standardly used.