System of musical notation without staves and notes, invented by John Curwen (1816–1880) in the middle of the 19th century on a basis of the principles of solmization and solfège , and once widely used by choral singers, for whom it simplifies the sight-reading of music. Tonic sol-fa notation is based on the old syllabic system of Do (Ut), Re, Mi, and so on, and takes the following form: d, r, m, f, s, l, t , the names of the notes being Doh, Ray, Me, Fah, Soh, Lah, Te. The substitution of ‘Te’ for the old ‘Si’ was made to avoid the duplication of the letter ‘s’ in the abbreviations. The range of voices being limited, upper and lower octaves can be sufficiently indicated by a simple stroke placed behind the letters in a higher or lower position, thus: d' represents the note an octave above d , which in turn is an octave above d′ . Accidentals (sharps and flats) are indicated by the addition of a letter ‘a’ (ra, ma, etc., or exceptionally ‘u’ for du) for flats and ‘e’ (de, re, etc., or…