GNU is an operating system that is free software—that is, it respects users’ freedom. The GNU operating system consists of GNU packages (programs specifically released by the GNU Project) as well as free software released by third parties. The development of GNU made it possible to use a computer without software that would trample your freedom.
Groff (GNU troff) is a typesetting system that reads plain text mixed with formatting commands and produces formatted output.
Texinfo is the official documentation format of the GNU project. It is used by many non-GNU projects as well.
The GNU Assembler, commonly known as gas or simply as, its executable name, is the assembler used by the GNU Project. It is the default back-end of GCC. It is used to assemble the GNU operating system and the Linux kernel, and various other software. It is a part of the GNU Binutils package.
The GAS executable is named as, the standard name for a Unix assembler. GAS is cross-platform, and both runs on and assembles for a number of different computer architectures.