A recent blog post on the rule of three ended with an example that depended on the comprehensive number for Minor Prophets. We quickly realized that we shouldn’t let too much time pass before addressing comprehensive numbers, or alternatively, numbers for comprehensive works.
Section 7.16 of the DDC Introduction explains that "comprehensive works treat a subject from various points of view within a single discipline. Comprehensive works may be stated or implied." Comprehensive works that are made explicit are, of course, easy to recognize. When the class-elsewhere note at 005.82 Data encryption reads, "Class comprehensive works on electronic signatures in 005.8" and the class-here note at 006.42 Optical pattern recognition reads "Class here comprehensive works on optical pattern recognition and computer graphics," the presence of a comprehensive works number is uncontroversial. But how can one recognize an implied comprehensive works number?
See references play a major role in helping the user to identify implied comprehensive works numbers. As stated in section 7.20 of the Introduction, "see references lead from a stated or implied comprehensive number for a concept to the component (subordinate) parts of that concept in a different notational hierarchy." For example:
358.17 Guided missile forces
Class here strategic missile forces, nuclear missile forces
Class strategic land missile forces in 358.1754
The see references in this entry give evidence that 358.17 Guided missile forces is the comprehensive works number for the subject in the caption. Specific points of view (that is, of air guided missile forces and of naval guided missile forces) are drawn off to other numbers. At 358.42 Bombing forces, we find air-to-underwater guided missile forces mentioned in the including note and find air-to-surface guided missile forces and comprehensive works on air guided missile forces mentioned in the class-here note. A see reference in this entry draws off air-to-air guided missile forces in turn to 358.43 Pursuit and fighter forces.
If we had a work on guided missile forces in general, it would be classed in 358.17 Guided missile forces. If, however, we had a work on air-to-surface guided missile forces, air-to-underwater guided missile forces (both 358.42) and air-to-air guided missile forces (358.43), we would use the comprehensive works number for air guided missile forces, i.e., 358.42 Bombing forces. (We would also choose 358.42 over 358.43 by the first-of-two rule.)
Section 7.20 of the Introduction continues: "throughout Table 2, see references (often in footnote form) lead from the implied comprehensive number for a jurisdiction, region, or feature to its subordinate parts in other classes." For example:
T2—496 *Balkan Peninsula
Class here *Danube River
*For a specific part of this jurisdiction, region, or feature, see the part and follow instructions under —4–9
The Danube flows through or borders numerous countries, including Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Moldova, Ukraine, and Romania. Class numbers have been designated specifically for the Danube River in Germany, i.e., T2—433 Bavaria (Bayern), and in Austria, i.e., T2—43612 Lower Austria (Niederösterreich). A work comparing the Danube River in Germany, Austria, and Serbia (T2—4971) should use the comprehensive works number for Danube River and be classed in 949.6 Balkan Peninsula.
As just seen, numbers for (implicit) comprehensive works are given for many
geographic jurisdictions, regions, and features. Similarly, they are often given for time periods. For example, at 941.081 Reign of Victoria, 1837–1901, we have the note "Class here
19th century." In conjunction
with this comprehensive treatment of the 19th century in the British
Isles are also see references for portions of the 19th century
classed elsewhere: For 1800–1820, see
941.073; for 1820–1830, see 941.074; for 1830–1837, see 941.075 (referencing
941.073 Reign of George III, 1760–1820;
941.074 Reign of George IV, 1820–1830, and 941.075 Reign of William IV, 1830–1837). What if we have a work on the history of the
pre-Victorian reigns from 1800 to 1837?
Should it be classed in 941.081, the comprehensive number for the 19th
century, or should it be classed in 941.07
Period of House of Hanover, 1714–1837?
answer is 941.07 Period of House of
Hanover, 1714–1837, since this number is in the upward hierarchy for all of
the relevant time periods and since 941.081 Reign of Victoria, 1837–1901 covers none of that same time.
Numbers for comprehensive works are also given for some combinations of subjects, especially when the comprehensive works number overrides the first-of-two rule. An example of this situation occurs in conjunction with the number for comprehensive works on midrange and personal computers, 004.16 Personal computers, even though 004.14 Midrange computers comes first.
Statements here about the number that a work should be classed in should be understood to address the assignment of the standard DDC number, captured in the 082 field (Dewey Decimal Classification Number) of the MARC bibliographic record. Numbers for component parts of the subject that are not chosen as the standard number should be considered for inclusion in the 083 field (Additional Dewey Decimal Classification Number).