A heritage unit or commemorative locomotive is a railroad locomotive painted in an honorary paint scheme; usually the paint scheme of a now-defunct railroad that merged with or was acquired by the locomotive's owner. Many of them are EMD SD70ACes from Union Pacific, Norfolk Southern, and even Canadian Pacific. The Union Pacific Railroad painted six "EMD SD70ACe"s in stylized paint schemes of six of its predecessors between 2005 and 2006. The Norfolk Southern Railway did the same in 2012 with 20 of its locomotives for its 30th Railroad Anniversary. 10 of them being EMD SD70ACes, while the others being GE ES44AC units. For its 40th anniversary in 2011, Amtrak painted four GE P42DCs, a P40DC, and an EMD F40PH converted to an NPCU into its older paint schemes. Several more were painted for its