| QR | Microbiology |
| 370 | Virology (QR355->QR502) |
| .O75 | Title of book (Origin and Evolution of Viruses) |
| 1999 | Publication Year |
| DS | Asian history |
| 796 | Chinese History (DS701-> DS799.99) |
| .H75 | Hong Kong History (social & intellectual aspects) (DS796.H75) |
| W55 | Author's name (Wiltshire) |
| 1991 | Year of publication |
Book A has no author - it is edited by a group of people, and each chapter is written by individuals. You can't really say "whose" work it is. The rules developed over the past 150+ years say that a book in this situation has its "main entry" as title. It is arbitrary, but it works.
Example B - is written by a single person, so it has the author as its main entry.
DS796 = Cities in China.
H7 is a pre-assigned number for Hong Kong. A book about Shanhgai would have a number of DS796.S2... These type of alphabet-number combinations are called "geographic subdivisions" or "Geographic Cutter".
Alphanumeric sequences are also often used to specify a narrow subject scope within a class number. For example, RA644 is for infectious diseases & different types of diseases are given pre-assigned Cutters.
RA644.C3 - Cholera
RA644.I6 - Influenza
RA644.M2 - Malaria
RA644.P9 - Polio
This video comes from Larentian Library at Douglas College in New Westminster BC. (1 min, 45 seconds)
