"The table below shows the section numbers of the manual followed by the types of pages they contain.

  1 Executable programs or shell commands
  2 System calls (functions provided by the kernel)
  3 Library calls (functions within program libraries)
  4 Special files (usually found in /dev)
  5 File formats and conventions eg /etc/passwd
  6 Games
  7 Miscellaneous (including macro packages and
    conventions), e.g. man(7), groff(7)
  8 System administration commands (usually only for root)
  9 Kernel routines [Non standard]"

So section 3 is a little wider than that, eg:

    $ apropos apache::xmlrpc
    Apache::XMLRPC::Lite (3pm) - mod_perl-based
       XML-RPC server with minimum configuration