Extensions

  By default, extensions to languages (such as nonstandard
  language constructs) are highlighted in the text.

  To disable the highlighting of extensions, choose Extensions
  from the Topic window's View menu.  To highlight extensions
  again, choose Extensions from the View menu again.

  A shaded check button to the left of the Extensions menu
  item indicates that highlighting is enabled.  The absence of a
  shaded check button indicates that highlighting is disabled.

  Additional topics:

  *   Topic Window Menus and Buttons

  *   Using Menus, Controls, and Dialog Boxes

  *   Bookreader Help Topics