allout-primary-bullet is a variable defined in `allout.el'.
Its value is

  • Automatically becomes buffer-local when set.
  • This variable is safe as a file local variable if its value
    satisfies the predicate `stringp'.

Bullet used for top-level outline topics.

Outline topic header lines are identified by a leading topic header
prefix, which is concluded by bullets that includes the value of this
var and the respective allout-*-bullets-string vars.

The value of an asterisk (`*') provides for backwards compatibility
with the original Emacs outline mode. See `allout-plain-bullets-string'
and `allout-distinctive-bullets-string' for the range of available

You can customize this variable.