I figured out how to properly generate an NC_ECANTREAD error (equivalent to the missing NC_ENOFILE) when the dap url is accessing data that does not exist. So now, the rule is roughly: 1. if the url does not exist: return NC_ECANTREAD 2. if the server returns other kinds of errors, then return NC_EDAPSVC. 3. If the server returns a response, but it is malformed, return NC_EDDS (or DAS, etc). =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: RVK-949505 Department: Support netCDF Priority: Critical Status: Closed