Trivirga in Square Notation

This is a close-up detail of a musical manuscript featuring a four-line staff with black ink notation. The central element is a trivirga, composed of three identical, vertically oriented square black note heads (punctum), each with a downward-extending stem attached to the right side, arranged horizontally on the third line of the staff.

The trivirga is a specific grouping in Gregorian chant notation, representing a sequence of three notes of the same pitch. It appears in medieval liturgical manuscripts and is essential to the study of early music and western plainchant.