mode-line-front-space

mode-line-front-space is a variable defined in `bindings.el'.
Its value is

(:eval (if (display-graphic-p) " " "-"))

• This variable may be risky if used as a file-local variable.

Documentation:
Mode line construct to put at the front of the mode line.
By default, this construct is displayed right at the beginning of
the mode line, except that if there is a memory-full message, it
is displayed first.