The standard six-line staff is constructed from the bottom with two normal staff lines, followed by a bold line, followed by two more normal staff lines, followed by a dashed line on top.   The bold line represents C.  The dashed line represents F#. This standard one octave staff has been repeated twice in the image above to show a span of two octaves.

Source: Directory of Music Notation Proposals, section/page: 10/1, 11/4, 13/1

Earliest Documentation: 1936

Manuscript Paper: Discontinuous Staves, Continous Staves