[VEX] point-prim-detail, Get these value in VEX.

------- point
<type> point(<geometry>geometry, string attribute_name, int pointnumber)
<type>[] point(<geometry>geometry, string attribute_name, int pointnumber)

ex). point(0,"P",@ptnum);

------- primitive
<type> prim(<geometry>geometry, string attribute_name, int primnumber)
<type>[] prim(<geometry>geometry, string attribute_name, int primnumber)

ex). prim(0,"area",@primnum);

------- detail
<type> detail(<geometry>geometry, string attribute_name, int ignored=0)
<type>[] detail(<geometry>geometry, string attribute_name, int ignored=0)

ex). If  detail has "min_val" value......
float val = detail(0, "min_val", 0);