century. Before then, accidentals only applied to immediately repeated notes or short groups when the composer felt it was obvious that the accidental should continue. The older practice continued in use well into the 18th century by many composers, notably Johann Sebastian Bach. The newer convention did not achieve general currency until early in the 19th century. See also Maneri-Sims notation Musical isomorphism, a mathematical concept which uses accidentals in its notation Notes Musical notation