<Tr> <Td> Transcription of the first few measures (full score; listen (help info)) </Td> </Tr> <P> Whereas the rules of notating rhythm in Mensural notation were in many ways different from the modern system, the notation of pitch already followed much the same principles . Notes were written on staves of five (sometimes six) lines, prefixed with clefs, and could be altered by accidentals . </P> <P> Mensural notation generally uses C and F clefs, on various lines . G - clefs, while used infrequently throughout the period, did not come into completely routine use until the later 16th century . Clefs were generally chosen to match the vocal range of a given voice, so as to avoid the need of ledger lines . Since middle C lies within that range for most voices, the C - clef is the one most frequently used . For mixed voices, a typical combination of clefs would have the bass clef (F on the fourth staff line) in the lowest voice, and tenor clef, alto clef and soprano clef (middle C on the fourth, third, and first staff line respectively) in the remaining voices . An alternative arrangement, known as chiavette, had the range of each voice shifted one third up, leading to a combination of F, C, C and G clefs . </P> <P> Clefs originally bore shapes more or less closely resembling the letter they represented, but came to develop more ornamental shapes over time . In the F - clef, the two arms of the "F" were changed into two dots sitting to the right of a vertical stem . All three elements could be further modified; in particular, they were often styled as if they were note heads . The C - clef remained a simple, often square, "C" - like shape in most manuscripts, but its arms tended to become hollow rectangles or rhomboids in later manuscripts and especially in music prints of the 16th century . The G - clef developed a curved ornamental swash typically attached to the top of the letter, which ultimately evolved into the loop shape of the modern form . </P>

The collection of parallel lines and spaces on which notes are written