Hi Abhisek,Thank you for the clarification. I have one more doubt about @DIN over irregular grids.I mainly deal with netcdf files of model outputs which usually contain bound information for depth. Hence, I frequently use @DIN function over Z axis assuming that Ferret takes care of irregular depth coordinate.Please correct me if I am wrong.You are right. Ferret does take care of irregular depth coordinates if the bound information is included in the netCDF file. (See below.)Regards,Ryo------------Actually, to confirm that, I did a little test a few months ago. I didn't bother to create a netCDF file but generated the depth axis and the data within Ferret. The script below is the test code. Note the EDGES qualifier of the DEFINE AXIS command, which defines both the gridpoints and bound information. The "v_iin" (vertically integrated meridional velocity) becomes zero at the bottom, proving that Ferret does use the correct thicknesses for each gridbox.let depv_edges = zsequence({0,100,300,600,1000,2000,4000}) !! let depw_dat = zsequence( {100,300,600,1000,2000,4000})define axis/z/depth/units=m/from_data/edges depv = depv_edges !! define axis/z/depth/units=m/from_data depw = depw_dat!! define axis/z/depth/units=m/from_data deppsi = depv_edgeslet v0 = zsequence({1, 3, 7, 3, -2, -1})let v = v0[gz=depv@ASN]set var/units="m/s"/title="v" vlet v_iin = v[z=0:4000@IIN]plot/line/symbol v_iin