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emacs outline mode

The outline mode lets you view sections of a large file.

-*- mode:outline -*-
The line above as the first line of a file tells emacs to use the outline mode.
See Debra Cameron, Bill Rosenblatt & Eric Raymond "Learning GNU Emacs", 2nd Ed,
pp 245-252
Enter outline mode: ESC-x outline-mode RETURN
C-c C-n next heading or subheading
C-c C-p previous heading or subheading
C-c C-f next heading of same level
C-c C-b previous heading of same level
C-c C-u up one level in outline
C-c C-t hide-body, hides all text
C-c C-a show-all, shows all text
C-c C-d hide subtree, hide the subtree where the cursor is
C-c C-s show subtree, show the subtree where the cursor is
C-c C-c hide entry