48 C.F.R. § 1239.7301
As used in this subpart-
Application means the software that resides above system software and includes applications such as database programs, word processors and spreadsheets. Application software may be bundled with system software or published alone.
Modernization means the conversion, rewriting or porting of a legacy system to a modern computer programming language, software libraries, protocols, or hardware platform.
Refresh means the periodic replacement of equipment to ensure continuing reliability of equipment and/or improved speed and capacity.
System software means a platform composed of operating system programs and services, including settings and preferences, file libraries and functions used for system applications. System software also includes device drivers that run basic computer hardware and peripherals.
Upgrade means an updated version of existing hardware, software or firmware. The purpose of an upgrade is improved and updated product features, including performance, product life, usefulness and convenience.
48 C.F.R. §1239.7301