Rastrum

rastra) or raster is a five-pointed writing implement used in music manuscripts to draw parallel staff lines when drawn horizontally across a blank piece of sheet music.

Rastrology, the study of the use of the rastrum, is a branch of music manuscript studies that uses information about the rastrum to help find the date and provenance of musical materials.

In recent years, rastra made of five ballpoint pens have been marketed to students and composers.

An alternative is to use a chalk board with staff lines etched in or taped on.

Another variant is the so-called "Stravigor", a wheeled instrument that Stravinsky attempted to patent around 1911.