Bruce Allen Dickey’s Lautus notation system has minor-third line spacing, but unlike Jason MacCoy’s Number Notes systems (above), which use three staff lines plus a ledger line, Lautus uses four staff lines per octave. The lines are G#, B, D, and F, and the top line (F) is bold. This pattern is similar to the four lines (G, B, D, and F) at the top of the traditional treble staff or the bottom of the traditional bass staff. Staves can be stacked to cover more than one octave as shown above, although Dickey recommends using a single octave staff with ledger lines to reduce visual density.
In place of a clef, a large Arabic numeral indicates the octave number.
Rhythmic notation is mostly traditional, but half, whole, and double whole notes are nontraditional, having solid black noteheads and multiple stems (hollow noteheads are not used). Half notes have one regular stem with a neighboring stem of half the height. Whole notes have a double stem, and double whole notes (breves) a triple stem. Quarter rests and shorter rests are traditional. Half rests and longer rests are nontraditional, having a similar appearance to the stems of the notes of corresponding duration, but with the rightmost line (or two) being thicker than the leftmost line. An optional variant of Lautus uses traditional rhythmic notation without any of these modifications.
Source: Bruce Allen Dickey, 2011
Similar Notations: Untitled by Arnold Schoenberg and 6-6 Klavar by Cornelis Pot, which also use a single bold line per octave.