Significant Entries

  Days that contain at least one entry or Day Note are
  displayed (flagged) in a different font in Month views.  You
  cannot flag particular entries or Day Notes.

  This feature is preset in the standard Calendar and is useful
  if you have relatively few entries.  To disable flagging in the
  Month view, use the Flag options in the Day view dialog box.

  An alternative method of flagging significant days is to choose

  Special from the Mark submenu of the Edit menu.  This
  method of flagging does not require the day to have any
  entries or Day Notes, and it can be set for any number of
  specific days.

  Additional topics:

  *   Customizing Day View Settings

  *   Options Menu