- "Toggle Font Lock mode.
-With arg, turn Font Lock mode off if and only if arg is a non-positive
-number; if arg is nil, toggle Font Lock mode; anything else turns Font
-Lock on.
-\(Font Lock is also known as \"syntax highlighting\".)
+ "Toggle syntax highlighting in this buffer (Font Lock mode).
+With a prefix argument ARG, enable Font Lock mode if ARG is
+positive, and disable it otherwise. If called from Lisp, enable
+the mode if ARG is omitted or nil.