hello,It's the problem>>>d1=[[0,0]]>>>d2=d1 #reference no copy>>>d2[0][0]=3>>>d2[[3,0]]>>>d1[[3,0]]okbut,>>>d1=[[0,0]]>>>d2=d1[:] #copy, no reference>>>d2[0][0]=3>>>d2[[3,0]]>>>d1[[3,0]]Why, is copy, no referenceHow copy a object?Excluse me, my englishGracias (Thank's),Saludos,Roland