Updated annually, each of the 40 volumes combines in one sequence the current edition of every Library of Congress classification schedule together with all additions, changes and deletions published in LC Classification - Additions and Changes through 2001 and the online LC Classification - Weekly Lists since 2002. Thus, for each classification schedule, catalogers need only look at this single source for current classification information. In addition Gale has added "G notes" to the text to clarify instructions and explain the "shorthand" phraseology used in the schedules.Schedules are also sold individually.