The document discusses different types of classified indexes and coordinate indexes. A classified index arranges topics hierarchically from general to specific, allowing for generic searches but requiring a two-step search process. Coordinate indexes combine individual index terms to create new classes, exemplified by the marginal-hole punched card system which indexed documents by punching holes in known positions on cards.

3. Classified Index
• is arranged in hierarchy of related
topics and working down to the
specific.

4. Advantages
 conceptually an aid to search.
Make searching simple if the users wants
to conduct generic searches; since the
hierarchy is visually presented.

5. Disadvantage
• A secondary file, an alphabetical list, is
necessary, so that a search will generally
require two-step procedure of going to the
alphabetical list to identify the right position in
the classified list.

6. Examples
Engineering Index. New York:Engineering
Information. Inc., 1884- .
Index Medicus. Bethesda,Md.:National Library
of Medicine, 1960- .
Index to Theses Accepted for Higher Degrees
in the Universities of Great Britain and Ireland. London: AsLib,
1953-.

8. Coordinate Index
are created by combining two or more
single index terms to create a new class.

9. For example , if the Individual index terms
“Black,” “Polecats,” and “Texas”
are combined, the result is distinctive class:
“Black Polecats of Texas”

10. A classic example of coordinate index is
the marginal –hole punched card
system.
Index terms were presented by notching
out holes in known positions around the
card

11. Marginal-hole punched card
Cats Dogs Cows
Birdboy, Samel W.
Cats and Cows. Journal of Animals, v.2 (Oct. 1990, 1-3)

12.  To Search this type of coordinate index, a needle was
inserted through a file of cards at the desired position
(e.g., “Cats” and “Dogs”) and the card were shaken so
that the notched cards would fall.
 In this case all cards with notches for cats and dogs
would drop out, thus identifying the papers that were
indexed under two terms

13.  Coordinate indexing was a natural consequence
of the application of the punch-card techniques
to information retrieval,
since the presence or absence of a hole in a card
can represent a binary indication of a specific bit
of in information.