Peter, I have just reread all your emails and I think I might understand what is going wrong. You are using 64-bit ints and floats in fortran, but you must surely tell the C compiler to do the same thing, right? Otherwise the C library will be using 32-bits not 64. But how one does this in AIX, I don't know... Ed Ticket Details =================== Ticket ID: DKO-246585 Department: Support netCDF Priority: Normal Status: Open