You can search for reference pages using a keyword search that works like the UNIX apropos (man -k) command. This feature uses a copy of the standard whatis database, which lists each reference page by its name and a brief description of its function.
To open the keyword search page, click the button in the Reference Pages category list. Here, the user searches for the string "ctype," receives a list of reference pages, and chooses to view wctype(3).