Howdy Andrew! Thanks for the example programs! I am using them as the basis for a new set of nc4 examples! You are correct, there is a bug netCDF-4.0-beta1 in the F77 -> C translation layer for the function nf_def_var_chunking. Whoops! Sorry about that. I have fixed the F77 problem and made a first stab at documenting these functions in the F77 manual. I am about to do the same for the F90 API and manual. I just wanted to let you know that I am making progress on this bug, and if you are content to use the F77 API (for the moment) you can get the netCDF-4 development snapshot tomorrow and give chunking and deflate a try. It seems to be working for me now. (Don't get it now, the fix hasn't percolated into it yet.) Thanks! Ed Ticket Details =================== Ticket ID: PMS-860672 Department: Support netCDF Priority: Normal Status: Open