Ok a work around can be used with :def axis/x/units="degrees_east"/modulo/from_data LONGITUDE=-1.8+i[i=1:100]*3.6
but the simpler line should work: def axis/x=1.8:358.2:3.6/units="degrees_east"/modulo LONGITUDE Patrick -- LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ Data Analysis and Visualization Engineer IPSL Global Climate Modelling Group --