C-h f then the command name, then click the link to see the source
code. Then, search for word map.
C-h m (describe-mode) is only for major mode. Minor mode doesn't have
such documentation.
i wrote a tutorial on table. Might be helpful.
〈Emacs: Working with Tables〉
http://xahlee.org/emacs/emacs_table.html
Xah