A zoom a viewer computes from the viewport's size: see GetZoom(ZoomMode, Double, Double, Int32, Double).
public enum ZoomMode
Spec #33 story 54 (viewer capability 14).
kind:method, kind:property, kind:ctor. Press Esc to clear.ActualSizeOne point of the page is one point on the screen.FitPageThe whole spread and the padding around it fit in the viewport.FitWidthThe spread and the padding beside it fill the viewport across the strip.