Usage: SET HIGHLIGHT_CHAR [BOLD|INVERSE|UNDERLINE|<string>]
  When the + option of IGNORE is used it highlights messages
  from the specific user.  The setting of this variable
  determines how the name is to be highlighted.

  If HIGHLIGHT_CHAR is not set to BOLD, INVERSE, or UNDERLINE, it is
  assumed to be some other arbitrary highlight string.  This is useful
  for setting it to an ANSI escape sequence (though DISPLAY_ANSI must
  be set on for them to display properly).

See Also:
  IGNORE
  SET DISPLAY_ANSI
