Using 3D studio max, how can define Editable poly,mesh and spline modeling?

you can right click on the object and select Editable poly  or apply a Editable Modifier and object and see the result.

If we are working on lines/curve we can make it editable spline by right clicking. 

If you are working on solid objects you can make it Editable Poly or Editable Mesh according to the needs.