Trims portions of a surface where it meets or bisects a curve, region, or another
surface.

If the SURFACEASSOCIATIVITY system variable is set to 1, the trimmed surface updates
whenever the trimming edges are modified.

The following prompts are displayed.

Select Surfaces or Regions to Trim

Select one or more surfaces or regions to trim.

Select Cutting Curves, Surfaces, or Regions

The curves that can be used as a trimming edge includes lines, arc, circles, ellipses,
۲D polylines, 2D spline fit polylines, 2D curve fit polylines, 3D polylines, 3D spline-fit
polylines, splines, and helixes. You can also use surfaces and regions as trimming
boundaries.

Select Area to Trim

Select one or more regions on a surface to remove.

Extend

Controls whether the cutting surface is trimmed to meet the edge of the trimmed surface.

Projection Direction

The cutting geometry is projected onto the surface. Controls the projection angle
as follows:

Automatic	When trimming a surface or region in plan, parallel view (for example, the default Top, Front, and Right view), the cutting geometry is projected onto the surface in the view direction. When trimming a surface or region with a planar curve in an angled parallel or perspective view, the cutting geometry is projected onto the surface in a direction perpendicular to the curve plane. When trimming a surface or region with a 3D curve in an angled, parallel or perspective view (for example, the default perspective view), the cutting geometry is projected onto the surface in a direction parallel to the Z direction of the current UCS.
View	Projects the geometry based on the current view.
UCS	Projects the geometry in the +Z and –Z axis of the current UCS.
None	The surface will only be trimmed if the cutting curve lies on the surface.