(a) Each major subject is designated a letter from the English alphabet excluding
“I” and “O” e.g. Science general is a major subject area and is classified as “Q”.
(b) Specific subjects within each major subject area are classified by using a
combination of two letters to indicate that it is a subdivision of the major subject
e.g. Mathematics is a subject within science and it is classified under “QA”.
Physics is a subject within science and is classified under “QC”.
(c) Topics under specific subjects are classified by addition of Arabic numbers to the two letters, for example
1.Calculus-a topic in mathematics is classified under “QA303.2”.
- Statistical physics–a topic in physics is classified under “QC 21.2”
In summary the Library of Congress Classification Scheme consists of the following components:
|Subject area||Major class||Sub-class||Class No.||Call No.|
|Broad subject||Specific subject||Specific topic|
The above subject is taken as an example of the major class, sub class and class numbers within the Library of Congress Classification Scheme. See the outline below of all subjects.
|A – General Works||PS – American Literature|
|B – Philosophy-Religion-Psychology||Q – Science|
|C – History (Civilization)||QA – Mathematics|
|D – History (Except America)||QB – Astronomy|
|E – American History||QC – Physics|
|F – Local American, Latin American History||QD – Chemistry|
|G – Geography-Anthropology||QE – Geology|
|H – Social Sciences||QH – Biology|
|J – Political Science||QK – Botany|
|K – Law||QL – Zoology|
|L – Education||QM – Human Anatomy|
|M – Music Scores||QP – Physiology|
|ML – Music (Literature of Music)||QR – Microbiology|
|N – Fine Arts||R – Medicine|
|P – Linguistics||S – Agriculture|
|PC – Romance Languages||T – Technology|
|PD – Germanic Languages||U – Military Science|
|PE – English Language||V – Naval Science|
|PQ – Romance Literature||Z – Bibliography, Library Science|
|PR – English Literature|