Attributes beginning with underscore are supposed to be reserved for Unidata use only and can be recognized by that underscore. I other attributes have been defined using leading underscore by others, then is is no way to tell them from Unidata attributes. You might notify the file producer to quit using leading underscores. =Dennis Heimbigner Unidata =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: BYC-698785 Department: Support netCDF Java Priority: Normal Status: Open