SoPrimitiveVertex(3) on Linux
The text 63b5b23e97cc, as Debian 4.0 (Etch) shipped it.
The SoPrimitiveVertex class represents a single vertex of a generated primitive. Instances of SoPrimitiveVertex are constructed when generating primitive data, primarily during an SoCallbackAction traversal. Depending on the context the vertex could represent a single 3D point, one of the two vertices in a line or one of the three vertices in a triangle.