A book on any particular subject may deal with that subject in various ways, from different standpoints or in different forms. It may be an encyclopaedia, a dictionary, a periodical, an advanced or elementary treaties or it may be written as a history, a philosophy, in essay or other literary form. Books on almost every subject frequently fall into one of these categories. All bibliographical classifications make provision for this”form” in books by the addition of the so-called form division.
500 Pure Science LA Sciences (Natural)
503 Dictionaries LA.5 Dictionaries
In each scheme, the subdivisions are used, with certain exceptions, throughout the whole classification:
510 Mathematics LB Mathematics
510.5 Periodicals LB.7 Periodicals
In the Expansive Classification the point (.) is a separating device only.
For more information read: Library Classification :: By C.K Sharma & Amit K. Sharma