A number of notation designers have used a five-line chromatic staff with one ledger line. This is a total of six lines spanning an octave, each spaced a whole step apart. The ledger line allows multiple one-octave staves to be “stacked,” placed contiguously for greater pitch range. In many cases these staves look exactly like the traditional staff (which would cause confusion), but some systems introduce bold lines or change the position of the ledger line.