For instance, in C major, a jazz musician may alter the V chord, G7 (G–B–D–F), with a flattened fifth, producing the chord G75 (G–B–D–F). An improviser might then choose a scale containing these four notes, such as the G whole tone scale, the G octatonic scale, or a mode of either D or A melodic minor ascending. In each case, the scale contains the chord tones G–B–D–F and is said to be compatible with it. This notion of "chord scale compatibility" marks a fundamental difference between jazz harmony and traditional classical practice.