There are two main types of NX Nastran licenses: desktop and enterprise. Desktop licenses have checksum control and are intended for use on the same computer that generated the input file. Enterprise licenses are more general and can be used with a dedicated solver computer, with high-performance computing, and across computers and platforms. Three new whitepapers discuss these topics: an introductory whitepaper compares the two license types and gives an overview of checksum control, and separate Femap and NX/Simcenter 3D whitepapers explain how users can select a license type and even generate a valid checksum without roundtripping a model using those programs.