Distribution of library materials in the library may be based on any one or more of the following features.
Access Consideration: The library may divide its collection into open access and closed-access. Generally microfilms, manuscripts, art books, and books which are very old and become rare, are placed under closed sequence.
Similarly classified documents, personal papers are also placed in closed sequence. Some libraries have a policy of putting publications upto a certain date of printing in closed sequence.
Size of Books: Dividing books into different sizes - normal, over size, under size - helps more efficient use of shelf space. Normal book size is demiquarto (5.5" X 8.75"). Books much smaller than this are placed under undersize sequence and much larger under oversize sequence,
Purpose: In an academic library, the collection is arranged by purpose for which patron will use them. Books with brief ready information such as dictionaries, encyclopaedias, bibliographies are kept in reference sequence. A set of books prescribed for various courses of study is placed in text book sequence.
Category of Materials by level or style of treatment is grouped in sequences such as children books, adult readings etc in public libraries.
Physical Aspects: Since material such as manuscripts on palm leaf, on clay tablets, or on chemically prepared base material such as gramophone record, tapes, films, paintings etc. present their own problem of preservation, they are arranged in a separate sequence.
Special Sequence: Sometimes a library specialising in a specific field may arrange books in the field concerned in a separate sequence e.g. Gandhiana Nehruana Publications of the parent institution, etc.