explnation vertices table\structure representation

in the pipeline :
points - > vertices → primitive
Im not sure im understand the table\structure representation of vertices.

Explanations are welcome.
vertices.toe (3.75 KB)

Note how many primitives there are in each Sphere. It is easier to see if you attach another SOP to DAT to each one and set them to ‘primitives’. In the latter sphere, there is only 1 primitive so all vertices are part of it and there numbering just counts up, where as the triangulated sphere only has 3 vertices per primitive so the number is 0, 1, 2 and repeat.
vertices.1.toe (3.8 KB)

thanks Ben,
in Houdini they pass along the point number
make more sense now .
vertices.jpg