The Library of Congress record for Meaning and mental representations illustrates why topic maps can be different from other information resources.
The record offers a default display, but also MARCXML, MODS, DUBLINCORE formats.
Each display is unique to that format.
Exercise: Requires pencil/pen, paper, scissors, tape.
Draw 4 unfolded cubes, ;-), just draw double lines across the paper and divide into 4 equal spaces.
Write down one of the values you see on the default page, say the title, Meaning and mental representation.
In the first box to your left (my right), write “Main Title.” Then go to each of the alternative formats and write down what subjects “contain” the title.
First difference, a topic map can treat the containers of subjects as subjects in their own right. (Important for mapping between systems and disclosing that mapping to others.)
Second difference, with the topic “unfolded” as it were, you can either view the other subjects that contain the subject of interest, or, you can cut the cube out and fold it up and display only one set of subjects at a time. You should fill out another set of boxes and make such cubes in preparation for the next difference.
Third difference, assuming that you have cut out two or more cubes and taped them together.
Rotate one of the cubes for a particular piece of information to a different face than the others.
Now we can see “Main Title” in the default system while seeing the author listing in Dublin Core. Our information system has become as heterogeneous as the data that it consumes.
Assignment: Do this exercise for 5 items in the LOC catalog (at least 3 fields) (your choice of items and fields) and prepare to discuss what insights this gives you about the items, their cataloging, the systems for classification or similar themes. Or a theme of your own. This entire area is very much in discovery mode.