How many netCDF formats are there, and what are the differences among them?
There are four netCDF format variants: • the classic format • the 64-bit offset format • the netCDF-4 format • the netCDF-4 classic model format (In addition, there are two textual representations for netCDF data, though these are not usually thought of as formats: CDL and NcML.) The classic format was the only format for netCDF data created between 1989 and 2004 by the reference software from Unidata. It is still the default format for new netCDF data files, and the form in which most netCDF data is stored. In 2004, the 64-bit offset format variant was added. Nearly identical to netCDF classic format, it allows users to create and access far larger datasets than were possible with the original format. (A 64-bit platform is not required to write or read 64-bit offset netCDF files.) In 2008, the netCDF-4 format was added to support per-variable compression, multiple unlimited dimensions, more complex data types, and better performance, by layering an enhanced netCDF access interface on
