point-num is present for half-edge(vex)
The environment is houdinifx software.
Point(point-level) only has 'POSITION' attribute.
Route: vertex -> half-edge -> primitives.
Vertices are shadow of one point. vertices form half-edge. half-edges form primitives
Point-num belongs vertex level.
Point-num stands for an unique half-edge.
Half-edge is directed, direction from started vertex to end vertex.
Half-edge belongs to unique primitive.
标签：num,point,vertex,vex,edge,half From： https://www.cnblogs.com/lnlidawei/p/16941341.html