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 Search by Keyword 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).