This chapter defines the format of two files used by the build. The two files are: tools_def.txt, which defines the location and options for third party tools and target.txt, which defines the top level default configuration. A third file, build_rule.txt, which specifies the rules for creating binary files, will not normally be modified by users, however since this file is closely coupled with the build system, certain changes to build tools will require updating (overwriting) the active copy. The format for build_rule.txt is not included in this document.