item action ~
indent allow backspacing over autoindent
-eol allow backspacing over end-of-line (join lines)
-start allow backspacing over the start position of insert; CTRL-W and
- CTRL-U stop once at the start position
+eol allow backspacing over line breaks (join lines)
+start allow backspacing over the start of insert; CTRL-W and CTRL-U stop
+ once at the start of insert.
+nostop like start, except CTRL-W and CTRL-U do not stop at the start of
+ insert.
When 'backspace' is empty, Vi compatible backspacing is used. You cannot
backspace over autoindent, before column 1 or before where insert started.