Due to the confusion in choosing coordinate systems, there occurred some misrepresentations/calculations of effective material properties of 0.67Pb(Mg1/3Nb2/3)O-3-0.33PbTiO(3) single crystals based on its single-domain data. This letter is to clarify these confusions by providing proper data set for each of the currently used coordinate systems. (C) 2004 American Institute of Physics.