Chain Indexing

What is Chain Indexing?

• Chain Indexing is a mechanical method to derive the subject heading from the class number of a document.
• Ranganathan's Idea about the role of classification was to analyze the subject of a document into its fundamental components and then to synthesis these components in a logical order in the classificatory language.
• According to Ranganathan, Chain Indexing is a " Procedure for Deriving class index entry (i.e. subject index entry) which refers from a class to its class number in a more or less mechanical way."
• The term ' chain ' refers to a modulated sequence of subclasses or isolates.
• Chain indexing was used in the British National Bibliography in the 1950s and 1960s until it was replaced by PRECIS-indexing.

Steps in Chain Indexing

1. Construction of the class Number of the subject of the Document
2. Representation of the Class Number in the form of a Chain
3. Determination of Links

• Sought Links (SL)

Sought links denote the concepts ( at any given stage of the chain) that the user is likely to use it as an access point.

• Unsought Links (USL)

Unsought links denote those concepts that are not likely to be used as access points by the user.

• False Links (FL)

False links are those that really do not represent any valid concept, mostly these are connecting symbols or indicator digits.

• Missing Links (ML)

Missing links represent those concepts that are not available in the preferred classification scheme; these are not inserted by the indexer by means of verbal extension at the chain-with-gap corresponding to the missing isolate in the chain whenever there is such a need.

4. Preparation of Specific Subject Heading

5. Preparation of Subject Reference Heading

6. Preparation of Subject Reference Entries

7. Preparation of Cross References, if any

8.Alphabetization

Advantages of Chain Indexing

1. Reduce duplication and save the time of the indexer.
2. Easy Indexing with any classification scheme
3. Easy to computerization
4. It is more or less a mechanical system and it is economic also.

Limitations of Chain Indexing

1. Too Much dependency on classification on the classification schemes.
2. Chain indexing provides only one specific entry and others are subject references.
3. There is a problem of a missing link in a chain indexing.
4. Chain disappears in each stage of deriving subject reference entries and thus it results in the loss of full context of the content of the document.