Any ICE tree that modifies point positions without adding or deleting points can be considered a deformation.
Deformations typically get the current point positions, modify them based on based on various other data like normal direction, and then set the new positions.
There are some compounds in the Deformations category on the Tasks tab of the preset manager that can be helpful when building deformations, including compounds for getting, setting, and modifying specific attributes and data types.
Deformations in the Simulation Region
Like any deformation, an ICE tree in the Simulation region of the construction is applied iteratively based on the point positions at the previous frame.
Footprints is an example of an ICE-based deformation that is meant to be used in the Simulation region. See Footprints (ICE) [Modeling and Deformation Basics].
Using the Simulate Particles Node
It is possible to use the Simulate Particles node to deform polygon meshes and other geometry types. You need to set at least one of PointVelocity and Force. If Mass is undefined, it is treated as 1.0. If Mass is 0.0, Force has no effect.
Autodesk Softimage v.7.5