gbk4_2nd_byte
#define gbk4_2nd_byte(v) ( (v) >= 0x30 && (v) <= 0x39 )
#define gbk4_2nd_byte(v) ( (v) >= 0x30 && (v) <= 0x39 )
#define gbk4_2nd_byte(v) ( (v) >= 0x30 && (v) <= 0x39 )
#define gbk4_2nd_byte(v) ( (v) >= 0x30 && (v) <= 0x39 )
#define gbk4_2nd_byte(v) ( (v) >= 0x30 && (v) <= 0x39 )
#define gbk4_2nd_byte(v) ((v) >= 0x30 && (v) <= 0x39)