Several grips are available for moving a point and changing the magnitude and direction
of tangents at specific points on splines, and in the U, V , and W directions on NURBS surfaces.

The 3D Edit Bar gizmo includes three grips:

• Triangle grip. Specifies the method for reshaping the selected object.
  
• Square grip. Reshapes the selected object by moving the base point or changing the tangent direction
  at the base point. Use the three axes to restrict the movement option to a specified
  axis. Similarly, the three squares that touch the square grip restrict the movement
  option to the specified planes.
  
• Tangent arrow grip. Changes the magnitude of the tangent at the base point. For example, lengthening
  the tangent arrow grip flattens the curvature of the surface at the point of tangency.
  The tangent arrow points in the direction of one of the surface’s U, V, or W axes, depending on the tangent direction specified in 3D Edit Bar Shortcut Menu.
  

The following prompts are displayed.

Select a NURBS Surface or Curve to Edit

Specifies the object to be modified. Valid objects include lines, arcs, circles, ellipses
and elliptical arcs, polylines, helixes, splines, and NURBS surfaces. Objects other
than surfaces can be converted to splines.

Select Point on Curve or Select Point on NURBS Surface

Specifies a base point on the selected curve or NURBS surface. Changes to the selected object are relative
to this point.

Base Point

Specifies a new base point on the curve or NURBS surface.

Displacement

Specifies a new base point by projecting the absolute coordinates entered onto the
selected curve or surface, when possible.

Undo

Cancels the previous change without exiting the command.

Exit

Cancels the current operation and returns to the previous prompt, or it exits the
command.