Edit modifiers are used to convert objects into a specific format. For example, an Edit Mesh modifier allows objects that can convert themselves into triangle meshes to be edited as an editable triangle mesh object (TriObject). An Edit Patch modifier allows objects that can convert themselves into patches to be edited as a patch mesh (Patch).
Edit modifiers typically allow the user to select sub-object elements of the object (vertices faces and edges in the case of the Edit Mesh modifier) and perform at least the standard transform, rotate, and scale transformations to them. They may also support additional operations such as the extrude option of the Edit Mesh modifier.