The hierarchy of the Classification is given by a differentiation of the whole body of knowledge into several levels, i.e., section, class, subclass, group and subgroup, in descending order of hierarchy.
22.
The hierarchy among subgroups is determined solely by the number of dots preceding their titles, and not by the numbering of the subgroups.
Example:
C 08 C
1
/
06
•
•
Preservation of rubber latex (preserving ingredients C 08 K)
1
/
065
•
•
Increasing the size of dispersed rubber particles
1
/
07
•
•
•
characterised by the agglomerating agents used
1
/
075
•
•
Concentrating
1
/
08
•
•
•
with the aid of creaming agents.
This example shows that three-digit, two-dot subgroups 1/065, 1/075 are hierarchically superior to the two-digit, three-dot subgroups 1/07, 1/08, respectively.
23.
The dots are also used in place of, and to avoid repetition of, the titles of hierarchically directly superior (less indented) groups.
Example:
A 63 H
3
/
00
Dolls
3
/
36
•
Details, Accessories
3
/
38
•
•
Dolls' eyes
3
/
40
•
•
•
movable.
Without the use of hierarchical levels, subgroup A 63 H 3/40 would have to have a title such as: "Movable dolls' eyes as details of dolls".
24.
The hierarchical classification using a six-dot subgroup is shown in the example B 64 C 25/30:
Section:
B
PERFORMING OPERATIONS; TRANSPORTING
Class:
B 64
AIRCRAFT; AVIATION; COSMONAUTICS
Subclass:
B 64 C
AEROPLANES; HELICOPTERS
Main group:
B 64 C
25
/
00
Alighting gear
One-dot subgroup:
25
/
02
•
Undercarriages
Two-dot subgroup:
25
/
08
•
•
non-fixed, e.g., jettisonable
Three-dot subgroup:
25
/
10
•
•
•
retractable, foldable, or the like
Four-dot subgroup:
25
/
18
•
•
•
•
Operating mechanisms
Five-dot subgroup:
25
/
26
•
•
•
•
•
Control or locking systems therefor
Six-dot subgroup:
25
/
30
•
•
•
•
•
•
emergency actuated.
Group B 64 C 25/30 actually concerns "emergency actuated control or locking systems for the operating mechanisms for retractable, foldable or the like non-fixed undercarriages used in alighting gear for aeroplanes or helicopters".
MULTI-PART TITLES
25.
Some titles may comprise two or more distinct parts separated by semicolons. Each part of these titles is to be interpreted as if it stood alone. This usually occurs when it is considered desirable to treat together distinct kinds of subject matter which cannot conveniently be covered by a single phrase.
Example:
A 01 B
3
/
10
•
•
•
Trussed-beam ploughs; Single-wheel ploughs.
REFERENCES
26.
In many cases, a class, subclass or group title, a guide heading or a note (see paragraph 29, below) contains a phrase in brackets referring to another place in the Classification. Such a phrase, called a reference, shows that the subject matter indicated by the reference is covered by the place (or places) referred to.