How to use 'Default Category' field for search?

Summary

How to use 'Default Category' field for search?

Content

Hi all

Steps:
1) Manage Requisitions > Search a requisition > Edit the requisition
2) Edit a line.
3) Click search button for Category Name field.
4) Click Advanced button.
5) Click 'Add field' button, and add 'Default Category' field.

Then, we can use 'Default Category' field for search category.
However, 'Default Category' is specified by setting. It means that 'Default Category' value is always same.
If this understanding is correct, we cannot understand usage of the field for search.
What situation needs the field for search? i.e. How situation does the produce suppose?

 

Thanks!

Wu