 An operation of change can be so constructed that it adjusts the position of the input sentence in an ordering to be the same as that of a reference sentence. This means that two sentences have to be specified in the input: the (input) sentence to be moved and the (reference) sentence indicating its new position. Hans Rott (2007, Other Internet Resources) called such operators two-dimensional. John Cantwell (1997) classified them as raising or lowering, depending on the direction of change. (See also Fermé and Rott 2004 and Rott 2009.)