Hi
Yes, a wall diaphragm is probably a better way of discribing it.
I have a small single storey timber building constructed from timber stud walls with plywood boarding. The external walls are timber stud inner leaf with a brick slip cladding system on the external face.
Although instinct tells me that the external wall panels will be sufficent I wouls still like to check them as a diaphragm so that I am satisfied that the building has lateral stability.
I haven't actually designed a timber wall for shear before.