An NC file is a file encrypted with mcrypt, a Linux crypting utility that allows users to encrypt and decrypt files or data streams. It contains a file encrypted with an algorithm, such as md5, tiger, or whirlpool, specified by the user and secured with a passphrase.

mcrypt is a tool that replaces the crypt() package and crypt(1) command. The program provides the option to encrypt and compress a file with GNU zip (gzip) compression, which appends the ".gz.nc" extension to the file, or encrypt and compress a directory as a TAR archive compressed with gzip, which appends the ".tar.gz.nc" extension to the file.

Data file created in the netCDF (network Common Data Form) format, a format used for storing multidimensional data in a manner independent of the platforms and disciplines for which it is used; often used by scientific researchers for GIS, atmospheric, climate, and ocean model data, as well as for data in other related fields; includes descriptive information about the data in addition to the data itself; used for storing and interchanging data.

NC files can be manipulated using Unidata's free netCDF tools, a set of libraries that provide interfaces in the Java, C, C++, Fortran, and Perl programming languages. The netCDF tools maintain backward compatibility with any previous file format versions. NC files are also supported by many other applications and command line utilities. The netCDF format is recognized by organizations such as NASA's Earth Science Data Standards group, the Open Geospatial Consortium, and the Federal Geographic Data Committee.