This regexp will be surrounded with \\\\( ... \\\\) when actually used.
Set this variable to \"\\\\sw\" if you want ordinary words or
-\"\\\\sw\\\\|\\\\s_\" if you want symbols (including characters whose
-syntax is \"symbol\" as well as those whose syntax is \"word\".
-
-The value nil has a special meaning: the abbreviation is from point to
-previous word-start, but the search is for symbols.
-
-For instance, if you are programming in Lisp, `yes-or-no-p' is a symbol,
-while `yes', `or', `no' and `p' are considered words. If this
-variable is nil, then expanding `yes-or-no-' looks for a symbol
-starting with or containing `no-'. If you set this variable to
-\"\\\\sw\\\\|\\\\s_\", that expansion looks for a symbol starting with
-`yes-or-no-'. Finally, if you set this variable to \"\\\\sw\", then
-expanding `yes-or-no-' signals an error because `-' is not part of a word;
-but expanding `yes-or-no' looks for a word starting with `no'.
-
-The recommended value is nil, which will make dabbrev default to
-using \"\\\\sw\\\\|\\\\s_\"."
+\"\\\\sw\\\\|\\\\s_\" if you want symbols (including characters
+whose syntax is \"symbol\" as well as those whose syntax is
+\"word\"). The abbreviation is from point to the start of the
+previous sequence of characters matching this variable.
+
+The default value of nil is equivalent to \"\\\\sw\\\\|\\\\s_\".
+
+For instance, suppose the current buffer is in `c-mode'. If this
+variable is nil or \"\\\\sw\\\\|\\\\s_\", then expanding
+`debug_print_in_' looks for a symbol starting with
+`debug_print_in_'. If you set this variable to \"\\\\sw\", that
+expansion looks for a word prefixed with `in_' (e.g., it would
+match `in_range', but not `in_close_range'). If expanding
+`debug_print_in' it would look for a word starting with
+`in' (e.g. `integer')."
:type '(choice (const nil)
regexp)
:group 'dabbrev)