CA Index Guide (Appendix I) 1994

Hierarchies of General Subject Headings

A publication of the Chemical Abstracts Service published by the American Chemical Society, and reproduced here with permission from the Chemical Abstracts Service.


The General Subject Index headings employed in CA indexes have been developed over the years by experts, both CAS staff and outside volunteer consultants, in various fields of chemistry and related sciences. The index headings chosen also reflect the evolution of terminology over a period of time. Because the overall CAS objective is to index a given subject as specifically as possible in light of the actual disclosure, a type of hierarchy of headings has developed naturally in a number of subject areas.

These inherent relationships have been codified and this appendix contains General Subject Hierarchies which have been identified and a Hierarchy Index. The hierarchies indicate relationships between general and more specific index headings in each subject area. Additional useful points of entry to the General Subject Index are thus provided for a given search topic.

Each heading currently used in the CA General Subject Indexis in one or more appropriate lists except that systematic and most common names for animals, bacteria, nonedible plants, and other organisms are excluded. Common names of the major plants used as feed and food are included, however, in the Food and Feed hierarchy.

As an example of the use of the Index Guide and the hierarchies together, consider a search on the subject of stacking faults. Since this term is not used as a CA index heading it will not be found in the Hierarchy Index. Therefore, the body of the Index Guide should be consulted where the following cross-reference will be found:

Stacking faults

See Crystal defects

The Hierarchy Index has the entry:

Crystal defects, 54a

Hierarchy 54 is devoted to Solids (the most general subject index heading for this subject area). Crystal defects is listed here under Crystals (a General Subject Index heading more specific than Solids but less specific than Crystal defects). Related General Subject Index headings with a degree of specificity greater than Crystal defects include: Color centers, Impurities and Impurity centers, Paramagnetic centers, and Stacking-fault energy, which may be selected for searching also.

Key to Hierarchies of General Subject Headings

43. Plant
               Forest <----------------(1)
                (Plant anatomy) <---------(3)
               * Plant cell
               * * Organelle [See Hierarchy 37] <----------(5)
               * Plant tissue
               * * Seed
               * * * Nut (seed)
               Plant physiol.  <--------------(4)
               * Plant growth and development
               * * Abscission
(2)----->      * * * Leaf abscission
               * * Etiolation
               * * (Nastic movement)  <-----------(3)
               * * * Epinasty
               * * * Hyponasty
               * Nyctinasty
               * * Tropism
               Plant reproduction
e              * Seed
               * Spore

54. Solids
a              Amorphous substances  <----------(1)
               * Crystal defects
               * * Color centers
               * * Impurities and Impurity centers
               * * Paramagnetic centers
(2) ---->      * * Stacking-fault energy
               * Crystal field
               * Crystal morphology
               * * Crystal dendrites
               * * Crystal whiskers
               * Crystallinity
               * Crystallites
               * Crystallization
               * * Crystal growth
  1. The most general index headings within a hierarchy are placed at the left margin.
  2. Increasing specificity of index headings is indicated by a series of dots and spaces preceding the individual terms. Thus, in the Solids heading example, the most specific index headings are preceded by two dots. In the Plant example, Leaf abscission has additional specificity. When Leaf abscission is the target of a search, it may be worthwhile to investigate Abscission or Plant growth and development for more general documents of interest.
  3. Terms of hierarchical importance but not used as General Subject Index headings have been added (in parentheses) to provide a logical framework for more specific terms appearing in the index.
  4. Text modifications (see Appendix II, ¶ 10) appear in lowercase on a separate line (indented under the index heading without the preceding dots.) These terms appear when only part of the index heading is applicable to the specific hierarchy. In the key example, the only relevant entries at the heading Plant are those in which test modifications begin with the term “physiol”.
  5. Cross references to hierarchies with greater specificity are shown in brackets on a separate line (indented under the index heading without proceeding dots).

The Hierarchy Index, following the sixty-four hierarchy lists, contains all the currently valid General Subject Index headings in a single alphabetic list with the numeric(s) and alphabetic(s) of the hierarchy list(s) on which the term appears.

Key to Hierarchy Index

(1)----->      Cottonseed 16f
               Cottonseed meal 16f, 16g
               Cottonseed oil 16f, 36a
               Cotyledon 43a, 43c
               Cough 30z
               Crystal defects 54a
               Crystal dendrites 54b
               Crystal field 13c, 54a  <---------- (2)
               Crystal field theory and Ligand field theory 54b
               Crystal growth 32a, 54b
               Crystal lattice dynamics 54b
               Crystal lattice energy 54b, 60a
               Crystal lattice statics 54b
               Crystal lattice sum 54b
               Crystallinity 54b, 54e, 56c
               Crystallites 39b, 54b
               Crystallization 12e, 32a, 39b, 47c, 52d, 54b, 55d, 55e, 58c
               Crystallization apparatus 5al
               Crystallography 51b, 51d, 51f
  1. General Subject Index headings are listed alphabetically.
  2. The numbers printed after the index headings refer to the sequentially numbered, alphabetically arranged hierarchies in which the heading will be found. An index heading may appear in more than one hierarchy. For example, Crystal field, is found in Hierarchy 13 (Electricity and Electric property) and also in Hierarchy 54 (Solids).

The alphabetics refer to subdivisions within each hierarchy which contain 20 terms. They allow the user to more easily locate the desired term in very large hierarchies. Note that the same term may appear more than once in the same hierarchy as indicated by multiple alphabetics.