Pocket part

The pocket part was first introduced in 1916 by the West Publishing Company to update McKinney's Consolidated Laws of New York.

[3] At regular intervals (usually annually), the publisher sends out a new pocket part, which is a saddle-stapled pamphlet printed on cheap newsprint.

Since the law is always changing, a pocket part may eventually grow into a separate softcover booklet to be shelved next to its hardcover counterpart.

[1][3] Eventually, when a pocket part becomes nearly as big as its parent book (because most of the parent book's sections have changed since it was originally released), the publisher sends out a new hardcover volume with all the intervening changes incorporated, and directs subscribers to discard the old volume and pocket part.

Modern imagesetters, platesetters, desktop publishing software, and offset printing have almost completely automated the process of typesetting such books.

An example of how pocket parts may outgrow the pockets. The ninth edition of Witkin's Summary of California Law was superseded by the tenth edition in 2005 after the pocket parts grew too big.