Auxiliary Clipping is turned on with View -> Auxiliary Clipping and it takes the location of the plane tool and hides all the geometry in the normal direction. Its very fast and doesn't create any new parts. And if you want some parts to not get clipped away, turn the effect for auxiliary clipping off for them on a part by part basis. That's a summary of basic auxiliary clipping.
How to turn on Auxiliary clipping.
Sometimes people decide they want to see a section of the model, so essentially they want two auxiliary clips with normals pointing away from each other. There are more complicated possibilities but this is the most common want/need. You can do this, but it doesn't require two plane tools and two auxiliary clipping options and keeping the plane tools coplanar. Its just one auxiliary clipping and one plane tool and a thickness (to ignore clipping). This is activated with a test: command, that is an EnSight command issued in the command windows (File -> Command ) like this. "test: thick_aux_plane #" where # is a distance of the thickness.
This command does aux clipping but preserves a slice of # from the clip plane with the rest (all geometry outside the slice) removed.
As shown below on the shuttle model. Here I used
test: thick_aux_plane .05
Moving the plane tool shows the interaction is still there.
Rotating the model you can see the effect more clearly
This is really nice because you can rotate the entire model to see from any direction, you can reissue the command to larger or smaller thicknesses, you can reposition the plane tool as normal by grabbing the origin for positioning or the X, Y, or Z labels for rotation (or use other methods), or you can turn off aux clipping for each part as a part setting. Lots of options.
Box Tool and Clip
Sometimes people have used the Box Tool to create a similar effect. That method is not dynamic, it still is quite powerful.