The Slice Mesh Surface tool 
on the Cloud/Mesh Tools Tab slices a Triangulated Mesh
Surface along a straight edge. It is used in the 3D Viewer. The sharp slice
will split the Triangulated Mesh into two new separate Meshes. This action is
undoable.
Holding down the “Ctrl” key on the keyboard while performing the slice will discard the smaller of the two split Meshes.
Holding down the “Shift” key will constrain or snap the slice edge to 45de.g. or 90de.g. intervals.
The slice will cut through all Meshes that are visible.