Use the View menu to choose between formats for
  displaying the namespace or to choose a tree style.

  The Browser provides two basic formats for displaying
  the namespace: outline and tree. The outline format
  indents to show the hierarchy of entries in the
  namespace. Lines connect the entries with the tree
  format.

  If you select the Display Tree format, Tree Style
  is activated. You then have a variety of choices for
  customizing the appearance of the tree.