标准ASCII二十号的含义

00000000	0	00	NUL(null)	空字符
00000001	1	01	SOH(start of headling)	标题开始
00000010	2	02	STX (start of text)	正文开始
00000011	3	03	ETX (end of text)	正文结束
00000100	4	04	EOT (end of transmission)	传输结束
00000101	5	05	ENQ (enquiry)	请求
00000110	6	06	ACK (acknowledge)	收到通知
00000111	7	07	BEL (bell)	响铃
00001000	8	08	BS (backspace)	退格
00001001	9	09	HT (horizontal tab)	水平制表符
00001010	10	0A	LF (NL line feed, new line)	换行键
00001011	11	0B	VT (vertical tab)	垂直制表符
00001100	12	0C	FF (NP form feed, new page)	换页键
00001101	13	0D	CR (carriage return)	回车键
00001110	14	0E	SO (shift out)	不用切换
00001111	15	0F	SI (shift in)	启用切换
00010000	16	10	DLE (data link escape)	数据链路转义
00010001	17	11	DC1 (device control 1)	设备控制1
00010010	18	12	DC2 (device control 2)	设备控制2
00010011	19	13	DC3 (device control 3)	设备控制3
00010100	20	14	DC4 (device control 4)	设备控制4
00010101	21	15	NAK (negative acknowledge)	拒绝接收
00010110	22	16	SYN (synchronous idle)	同步空闲
00010111	23	17	ETB (end of trans. block)	传输块结束
00011000	24	18	CAN (cancel)	取消
00011001	25	19	EM (end of medium)	介质中断
00011010	26	1A	SUB (substitute)	替补
00011011	27	1B	ESC (escape)	溢出
00011100	28	1C	FS (file separator)	文件分割符
00011101	29	1D	GS (group separator)	分组符
00011110	30	1E	RS (record separator)	记录分离符
00011111	31	1F	US (unit separator)	单元分隔符
00100000	32	20	(space)	空格