When a song or chord progression is said to be in a particular key, it means that the melody or chords used are based upon a particular major or minor scale. As mentioned in the previous section, a song or chord progression in the key of A major would contain a melody which uses notes from the A major scale. The key of a melody line is indicated by the key signature, which indicates which major or minor scale the song uses. The following diagram lists key signatures for each major key and its relative minor key. The notes in the relative minor scale are the same as the notes in the major scale, except that they start and end on different notes. For example, the C major and A minor scales contain the same notes and therefore have the same key signature. A minor is the relative minor to C major.