4. Semantic Relationships used in Controlled Vocabularies

4.1 Semantic Linking | 4.2 Equivalency | 4.3 Hierarchy | 4.4 Associative

There are three types of relationships used in controlled vocabularies:
a) Equivalency (see section 4.2)
b) Hierarchy (see section 4.3)
c) Association (see section 4.4)

4.1 Semantic Linking (8.1)

The relationships among terms in a controlled vocabulary are indicated by semantic linking.

Semantic linking encompasses various techniques and conventions for indicating the relationships among terms.

Formats for displaying semantic relationships are described in Section 5. Displaying Controlled Vocabularies; this section is concerned with defining and illustrating the relationships themselves. Table 1 illustrates the basic types of relationships and provides some simple examples. Each of these types is covered in detail in 4.2 through 4.4.

Indicating Relationships Among Terms (8.1.1)

A basic property of relationships in controlled vocabularies is that they are reciprocal; hat is, each relationship indicated between Term A and Term B has a corresponding relationship from Term B to Term A. This rule is observed for all types of relationships.

The conventional abbreviations for relationship indicators are used in the examples below. Additional abbreviations for specialized purposes are found in the following sections.

The relationship indicators are always paired operators. Some indicators are symmetric while others are asymmetric as illustrated below:

• Related Term (RT) is symmetric:
If Term A RT Term B, then Term B RT Term A

• Preferred Term (Equivalency) – USE and UF are asymmetric:
If Term A USE Term B, then Term B UF Term A

• Hierarchical Relationships – BT and NT:
If Term A BT Term B then Term B NT Term A.

To be continued: 4.2 Equivalency | 4.3 Hierarchy | 4.4 Associative

| Table of Contents |
| 1. Why Vocabulary Control | 2. Principles | 3. Structures | 4. Semantic Relationships |
| 5. Displays | 6. When to use | 7. Examples of use | 8. About Z39.19 |
©NISO, 2005 http://www.niso.org/

Source: Based on ANSI/NISO Z39.19-2005 ISBN: 1-880124-65-3 
Guidelines for the Construction, Format, and Management of Monolingual Controlled Vocabularies