[1] Charles Ammi Cutter (1837–1903), inspired by the decimal classification of his contemporary Melvil Dewey, and with Dewey's initial encouragement, developed his own classification scheme for the Winchester, Massachusetts town library and then the Boston Athenaeum,[2] at which he served as librarian for twenty-four years.
[4] He devised the Expansive Classification in response, to meet the needs of growing libraries, and to address some of the complaints of his critics.
[8] Library historian Leo E. LaMontagne wrote: Cutter produced the best classification of the nineteenth century.
While his system was less "scientific" than that of J. P. Lesley, its other key features – notation, specificity, and versatility – make it deserving of the praise it has received.
[10] It did not catch on as did Dewey's system because Cutter died before it was completely finished, making no provision for the kind of development necessary as the bounds of knowledge expanded and scholarly emphases changed throughout the twentieth century.
[15] Most call numbers in the Expansive Classification follow conventions offering clues to the book's subject.
Geographical numbers are often further expanded decimally to represent more specific areas, sometimes followed by a capital letter indicating a particular city.
When appropriate, the second line may begin with a 'form' number—e.g., 1 stands for history and criticism of a subject, 2 for a bibliography, 5 for a dictionary, 6 for an atlas or maps, 7 for a periodical, 8 for a society or university publication, 9 for a collection of works by different authors.