Looked at the hdf5 code for version 1.8.17 and it seems to do pretty much the same as what we do in NC_check_file_type. So I guess I am going to need a .nc or .hdf5 file that exercises this bug. =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: UBS-599337 Department: Support netCDF Priority: Normal Status: Open =================== NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.