); char = class(dref)

                  or

               [1,1] = size(dref); cell = class(dref)

               When 'dref' designates a non-inertial frame, the
               orientation of the frame is evaluated at an epoch
               dependent on the frame's center and, if the center is
               not the observer, on the selected aberration
               correction. See the description of the direction
               vector 'dvec' for details.

      dvec     Pointing vector emanating from t