The CIPA standard (CIPA DC-X011,
http://www.cipa.jp/image-stab... ) that defines how to measure image stabilization performance considers IBIS “optical”, see page 50:
> Out of the examples of a motion blur correction given below in A-3-3-3, a) and b) are called optical methods […].
A-3-3-3 b):
> A method where displacement in the image caused by camera shake is corrected by rotating or moving the imaging element in a perpendicular direction relative to the optical axis using the output of a blur detection means.