Page 96 - Cataloging and Classification for Library Technicians, 2nd Edition

82 Cataloging and Classification for Library Technicians
A de tailed discussion of the four vol umes of DDC 21 fol lows. Vol -
ume one is ti tled In tro duc tion. Ta bles. The use of this ref erence book
and the prin ciples of this clas sification scheme are ex plained in the in -
troduction sec tion. Some main con cepts are es pecially important to re -
member. The ba sic classes are ar ranged by tra ditional ac ademic dis-
ciplines, not by sub ject. A given sub ject may be found in more than one
place, de pending on the dif ferent as pects of the sub ject. For ex ample, a
book on the topic of Internet may be given dif fer ent clas si fi ca tion
num bers, ac cord ing to DDC 21. The num ber 004.678 is used if the
book is an in terdisciplinary work about the Internet and con tains in for-
mation about computer hard ware. If the book does not con tain much
information about computer sci ence, but the em phasis is on search and
retrieval, number 025.04 would be used. For works that de scribe
Internet in for ma tion re sources de voted to spe cific dis ci plines and
subjects, 025.06 is as signed, and, fi nally, works on Internet access
pro vid ers and works on eco nomic and pub lic pol icy is sues con cerning
the Internet are clas sified as 384.33.
The en tire world of knowl edge is di vided into ten main classes.
The ten classes are fur ther di vided into ten di visions, and each di vi-
sion is di vided into ten sec tions. All clas sification num bers are three-
digit num bers, such as 000, 130, 269, etc. In the three-digit number,
the first digit in dicates the main class, the sec ond digit in dicates the
division, and the third digit in dicates the sec tion. Fol lowing the three-
digit num ber is a dec imal point after which may be additional dig its
that more spe cifically de fine the sub ject.
For ex ample, num ber 025.0 in dicates the main class Gen er al ities.
The mid dle num ber 2 in di cates di vi sion Li brary and in for ma tion sci-
ences, and num ber 5 in dicates the sec tion Op er a tions of li brar ies, ar-
chives, in for ma tion cen ters. To be more spe cific, the num ber 025.43
as the clas sification num ber for a book in dicates that the book is
about li brary clas si fi ca tion sys tems.
Seven ta bles used to limit the as pect of a sub ject are in cluded in
volume one of DDC 21. For ex amples, from Ta ble 1, “Stan dard Sub di -
visions,” num ber 092 in dicates per sons un der a main topic. From Ta -
ble 2, “Geo graphic Areas, Pe riods, Per sons,” number 73 means United
States under a main topic. The same kind of ar rangement can be found
in Ta ble 3A, “In dividual Au thors”; Ta ble 3B, “More Than One Au -
thor”; Ta ble 3C, “No tation to Be Added”; Ta ble 4, “Sub divi sions of