In the measure (bar) where it appears, an accidental sign raises or lowers the immediately following note (and any repetition of it in the bar) from its normal pitch, overriding the key signature. A note is usually raised or lowered by a semitone, and there are double sharps or flats, which raise or lower the indicated note by two semitones. Accidentals usually apply to all repetitions within the measure in which they appear, unless canceled by another accidental sign, or tied into the following measure. If a note has an accidental and the note is repeated in a different octave within the same measure the accidental is usually repeated, although this convention is far from universal.