- "Toggle Hide-Ifdef mode. This is a minor mode, albeit a large one.
-With ARG, turn Hide-Ifdef mode on if arg is positive, off otherwise.
-In Hide-Ifdef mode, code within #ifdef constructs that the C preprocessor
-would eliminate may be hidden from view. Several variables affect
-how the hiding is done:
+ "Toggle features to hide/show #ifdef blocks (Hide-Ifdef mode).
+With a prefix argument ARG, enable Hide-Ifdef mode if ARG is
+positive, and disable it otherwise. If called from Lisp, enable
+the mode if ARG is omitted or nil.
+
+Hide-Ifdef mode is a buffer-local minor mode for use with C and
+C-like major modes. When enabled, code within #ifdef constructs
+that the C preprocessor would eliminate may be hidden from view.
+Several variables affect how the hiding is done: