A 2-line staff is used, with the lower line representing E. Above and below the staff a ledger line is used to represent C. Between any two adjacent lines there are three elevations on which notes can be placed. These elevations are made easier to distinguish because the notehead is given a semicircular shape when it rests against a line. Rhythmic notation is mostly traditional.
In Diatonic Twinline the notehead color corresponds to the 7-5 pitch pattern, the black and white color pattern of the piano keys. De Vries intended for Diatonic Twinline to be a temporary, transitional system for those moving from traditional notation to Chromatic Twinline (in which the semicircles are black and the ovals are white, a 6-6 pitch pattern).
Earliest documentation: 1986
Source: Directory of Music Notation Proposals, section/page: 10/11, 11/2, 13/25