CHAPTER 6 A Reference for Bison Specifications In this chapter we describe the syntax of bison programs, along with the various options and support functions available. POSIX yacc is almost an exact subset of bison, so we note which parts of bison are extensions beyond what POSIX requires. After the section on the structure of a bison grammar, the sections in this chapter are in alphabetical order by feature. Structure of a Bison Grammar A bison grammar consists of three sections: the definition section, the rules section,