Key signature

What it means

The key signature (German Generalvorzeichen, also called Vorzeichnung) is the group of sharps or flats that stands at the beginning of every staff line after the clef. It fixes which notes are as a rule raised or lowered throughout the piece and spares writing the same signs anew in every bar. It applies in all octave registers and remains in force until a new key signature replaces it.

In the notation

The signs stand in a fixed order: sharps follow the series F♯, C♯, G♯, D♯, A♯, E♯, B♯, flats the reverse series B♭, E♭, A♭, D♭, G♭, C♭, F♭. Each sign also has its fixed place on the staff, which differs between clefs. With every new system the key signature is repeated. If the key changes in the course of the piece, the new key signature usually stands after a double bar; if accidentals are dropped, naturals indicate this.

Musical use

The key signature does not name the key but only the stock of raised or lowered notes. The same key signature applies in each case to a major key and its relative minor — two sharps, for instance, for D major and B minor — and which of the two is meant is revealed only by the music itself: final note, emphasis on the tonic, occurrence of the leading tone. In minor the raised seventh degree never appears in the key signature but always as an accidental within the bar. In modal and in older music, moreover, the connection between key signature and key is looser than in major–minor tonality.

The key signature is to be distinguished from the accidental: the latter stands within the bar, applies only to the notated octave register, and loses its effect with the bar line.

Performance practice

Before the first note, say the accidentals aloud and name the notes concerned — a glance at the number of signs alone does not suffice. In minor, check expressly whether the leading tone appears in the score as an accidental. At every change of line, glance briefly at the key signature; it may have changed compared with the previous line.