usr/src/cmd/struct/b.h

extern int xxindent, xxval, newflag, xxmaxchars, xxbpertab;
extern int xxlineno;            /* # of lines already output */
#define xxtop   100             /* max size of xxstack */
extern int xxstind, xxstack[xxtop], xxlablast, xxt;
struct node
        {int op;
        char *lit;
        struct node *left;
        struct node *right;
        };