Help using Classmarks

What is a classmark? It is the shelf location code usually written on the spine of the book. Use the classmark to locate where the book is on the shelf.

The Library uses three main classification schemes: Bliss, Dewey and Library of Congress.


Bliss classification

The Bliss Classification uses letters and numbers and looks a little bit like a UK postcode. Books are shelved alphabetically. MT is shelved before MU. MU is shelved before MUDV.

Within each subject books are shelved alphabetically according to the author or first word of the title – so MUDV/Abr is shelved before MUDV/Wil.

Please note that upper case letters are generally shelved in front of lower case ones.

Bliss is essentially an alphabetical classification, and uses a combination of letters and numbers to order books by subject. So ‘I’ appears before ‘IA’, which in turn precedes ‘IB’, and so on. In this way IC is shelved before ICA, ICB etc. For example:

63 M       = European history
63 MV    = European history –Britain
63 MVO = European history –Britain– 1640-1660

In subjects such as literature and philosophy it is often the author or philosopher that is the subject of the shelf mark.  For example:

3 YN                       =             English literature – 1830-1880
3 YN D                   =             English literature – 1830-1880 – Author beginning with ‘D’
3 YN D53               =             English literature – Dickens
3 YN D53a             =             English literature – Dickens – Critical works

Once you have both the location and the shelf mark, use the signs on the ends of each bay of shelves to help you find the item that you require. It should be noted that the signs do not always provide an exhaustive list of subjects, but are a guide to the more significant areas of the collections.

Although Bliss is broadly speaking an alphabetical classification system, there are a number of additional rules that may alter where an item would be found:

1. Numbers file in decimal order

For example, 57 precedes 6, or 352 precedes 75

2. Numbers file before letters

For example, XTR6 precedes XTR followed by a letter or QXP1 precedes QXP

3. Filing order of upper and lowercase letters

When looking at letters forming part of a row of a shelf mark, capital letters will precede lower case letters. This is commonly found in literature (including Area Studies) and philosophy.

3 YN D35               – English literature 1830-1880 – Dickens
3 YN D53E 994         – Capital ‘E’ – original work – The Uncommercial Traveller and other stories
3 YN D53PD 993      – Capital ‘PD’ – original work – Oliver Twist (1993 edition)
3 YN D53PDa Par     – Capital ‘PD’ – original work but lower case ‘a’ signifies critical work

– The companion to Oliver Twist by David Paroissien

3 YN D53a Col          – Lower case ‘a’ – general critical work – Dickens and Crime by Philip Collins

However, items where the second row of the classmark is entirely in capital letters will file at the end of a particular sequence. This is commonly found in history and the social sciences (including Area Studies), art and, to a lesser extent, film and media. For example 63 MVTCHUwill file after 63 MVT Tee.

63 MVT                  – British history 1900-1950
63 MVT Tee           – British history 1900-1950 – General Works

Britain, 1906-1951 : a welfare state by Peter Teed

63 MVT CHU             – British history 1900-1950 – Churchill – Autobiography

My early life by Winston S. Churchill

63 MVT CHU Gar       – British history 1900-1950 – Churchill – Biography

Churchill in his time by Brian Gardner


Other information

In some collections, most notably Art, large books are shelved in a separate sequence – indicated by the prefix ‘f’ or ‘folio’ before the location code

  • Some subject collections have a Rapid Reference section, where general reference works such as dictionaries and encyclopaedias may be found
  • There are designated re-shelving areas for recently-used material – these can be shelving bays or labelled trolleys, and are indicated on the library floor plans
  • Please remember that some items are held in the closed access stacks – Please ask at Issue Desk, 4th floor, South Block, or see our website for further details
  • All books related to Latin America, the Caribbean, United States, and Commonwealth studies are held in their respective area collections


Dewey Classification

The Dewey Classification uses only numbers. 016 is shelved before 016.7 and 016.7 is shelved before 016.78.

Within each subject books are shelved alphabetically according to the author or first word of the title, hence 016.78 [Abraham] is shelved before 016.78 [Williams].

This scheme uses numbers to code subjects. It can be found in the Rapid Reference Collection, the Music Library, and the Book Studies and Librarianship Collections. It is also used in the Rapid Reference sections of some collections to organise reference books such as dictionaries, bibliographies and encyclopedias.

Books are arranged on the shelf according to the code in a straightforward numerical sequence. In very general terms the subjects are arranged as follows:

  • 000 – Computer science, Library and Information science & general work
  • 100 – Philosophy and psychology
  • 200 – Religion
  • 300 – Social sciences
  • 400 – Language
  • 500 – Science
  • 600 – Technology
  • 700 – Arts
  • 800 – Literature
  • 900 – History, geography & biography

More detailed breakdown is possible using a decimal point.

To distinguish between books sharing the same number the digits may be followed by a name or word in square brackets.

Some examples:

The present state of scholarship in the history of rhetoric : a twenty-first century guide / edited by Lynée Lewis Gaillet with Winifred Bryan Horner. 

SHL 4th Floor Rapid Reference 016.8 [Present] REFERENCE ONLY

Desire by gender and genre in trouvère song / Helen Dell.

SHL Goldsmiths’ Library Reading Room 784 [Dell] AVAILABLE

Book practices and textual itineraries : tracing the contours of literary works / general editors : Nathalie Collé-Bak, Monica Latham and David Ten Eyck.

SHL Goldsmiths’ Library Reading Room 784 [Dell] AVAILABLE


Library of Congress

The Library of Congress Classification uses letters and numbers. Books are shelved alphabetically according to a subject code, hence L is shelved before LE. Read the number as a whole number: 1, 36, 2730. Any following lines are a combination of a letter and numbers. Read the letter alphabetically, and read the number as a decimal, eg: .S32 = .32 A last line is the year the book was published.

This is used in some of the Area Studies Collections of the Senate House Library. Superficially Library of Congress Classification resembles BLISS in that it always starts with a letter. The letters relate to the subject and are in normal alphabetical order.

  • A– General Works
  • B – Philosophy, Psychology, Religion
  • C – Auxiliary sciences of history
  • D – World History
  • E-F – History of the Americas
  • G – Geography, Anthropology, Recreation
  • H – Social Sciences
  • J – Political Science
  • K – Law
  • L – Education
  • M – Music and Books on Music
  • N – Fine Arts
  • P – Language and Literature
  • Q – Science
  • R – Medicine
  • – Agriculture
  • T – Technology
  • U – Military Science
  • V – Naval Science
  • Z – Bibliography. Library Science

However the middle section of the shelf mark contains letters and numbers divided by a decimal point:

  • Numbers in the first part of the shelf mark are in numerical order:
  • Numbers in the second part of the call number, after the decimal point,  are in decimal order.
  • There may be a third set of letters and numbers. These will also be in alphabetical and decimal number order, even though the decimal point will not be shown.
  • The last part of a call number may be a year. This indicates the publication date.

For example:

The Latin American revolution : politics and strategy from Apro-Marxism to Guevarism / [by] Donald C. Hodges.


Peru, 1890-1977 : growth and policy in an open economy / Rosemary Thorp and Geoffrey Bertram.