The standard staff has two groups of three solid lines with groups of three ledger lines appearing above, below, and between them as needed. The three solid staff lines represent the group of three black notes on the piano keyboard (F#/Gb, G#/Ab, A#/Bb). The three ledger lines represent C, D, and E. Like Parncutt’s other notation designs, the staff is aligned with the 7-5 pitch pattern, even though the lines and ledger lines have a 6-6 pitch pattern.
Earliest documentation: 1990
Source: Directory of Music Notation Proposals, section/page: 13/64