selecting a major mode -- more newbie questions

[Robert P. J. Day]

  just to make sure i've got a complete list, i see four ways to 
invoke a major mode when editing a file -- any other ways i've left
out?  (the examples i show are based on my wanting to edit XML)

1) explicitly with "M-x" <modename>

2) adding to .emacs the appropriate auto-mode-alist setting, as in:

  (add-to-list 'auto-mode-alist '("\\.xml\\'" . xml-mode))

3) adding a directive in the first non-blank like, as in

  <?xml version='1.0' ?> <!-- -*- xml -*- -->

  (or whatever the comment structure is for that type of data)

4) adding (within comments at the bottom of the file):

  <!-- Local variables: -->
  <!-- mode: xml -->

 
does that just about do it?  have i missed anything?  thanks for 
your patience; i'm making progress.

rday