A separator delimits character-strings.  It can be one character or two
  contiguous characters.  The following characters are recognized as
  separators:

      space      ( )            quotation mark         (")
      comma      (,)            apostrophe             (')
      semicolon  (;)            pseudo-text delimiter  (==)
      period     (.)            horizontal tab
      colon      (:)            left (() or right ()) parenthesis