Key signature A minor as each accidental may be notated explicitly as required, or the piece may be modal or atonal. An example is Bartók's Piano Sonata, which has no fixed key and is highly chromatic. If not bound by common practice conventions, microtones can also be notated in a key signature; which microtonal symbols are used depends on the system. The common practice period conventions are so firmly established that some musical notation programs have been unable to show nonstandard key signatures until recently. The use of a one-flat signature developed in the Medieval period, but signatures with more than one
Quarter note Quarter note A quarter note (American) or crotchet (British) is a note played for one quarter of the duration of a whole note (or semibreve). Often, musicians will say that a crotchet is one beat, but this is not always correct, as the beat is indicated by the time signature of the music; a quarter note may or may not be the beat. Quarter notes are notated with a filled-in oval note head and a straight, flagless stem. The stem usually points upwards if it is below the middle line of the stave or downwards if it is on or