Symbol: TCP_X2
usr/src/uts/common/inet/ipf/netinet/ip_compat.h
1790
# define TCP_X2(x) (x)->th_x2
usr/src/uts/common/inet/ipf/netinet/ip_compat.h
733
# define TCP_X2(x) ((x)->th_xoff & 0xf)