CCITT Draft Recommendation T.4                      PAGE   6



         01010011        8       50
         01010100        8       51
         01010101        8       52
         00100100        8       53
         00100101        8       54
         01011000        8       55
         01011001        8       56
         01011010        8       57
         01011011        8       58
         01001010        8       59
         01001011        8       60
         00110010        8       61
         00110011        8       62
         00110100        8       63
 
CCITT Draft Recommendation T.4                      PAGE   7



         Table 1b. Make Up White Codes
         Code            Lng     Run
         ---------------------------
         11011           5       64
         10010           5       128
         010111          6       192
         0110111         7       256
         00110110        8       320
         00110111        8       384
         01100100        8       448
         01100101        8       512
         01101000        8       576
         01100111        8       640
         011001100       9       704
         011001101       9       768
         011010010       9       832
         011010011       9       896
         011010100       9       960
         011010101       9       1024
         011010110       9       1088
         011010111       9       1152
         011011000       9       1216
         011011001       9       1280
         011011010       9       1344
         011011011       9       1408
         010011000       9       1472
         010011001       9       1536
         010011010       9       1600
         011000          6       1664
         010011011       9       1728
 
CCITT Draft Recommendation T.4                      PAGE   8



         Table 2a. Terminating Black Codes
         Code            Lng     Run
         ---------------------------
         0000110111      10      0
         010             3       1
         11              2       2
         10              2       3
         011             3       4
         0011            4       5
         0010            4       6
         00011           5       7
         000101          6       8
         000100          6       9
         0000100         7       10
         0000101         7       11
         0000111         7       12
         00000100        8       13
         00000111        8       14
         000011000       9       15
         0000010111      10      16
         0000011000      10      17
         0000001000      10      18
         00001100111     11      19
         00001101000     11      20
         00001101100     11      21
         00000110111     11      22
         00000101000     11      23
         00000010111     11      24
         00000011000     11      25
         000011001010    12      26
         000011001011    12      27
         000011001100    12      28
         000011001101    12      29
         000001101000    12      30
         000001101001    12      31
         000001101010    12      32
         000001101011    12      33
         000011010010    12      34
         000011010011    12      35
         000011010100    12      36
         000011010101    12      37
         000011010110    12      38
         000011010111    12      39
         000001101100    12      40
         000001101101    12      41
         000011011010    12      42
         000011011011    12      43
         000001010100    12      44
         000001010101    12      45
         000001010110    12      46
         000001010111    12      47
         000001100100    12      48
         000001100101    12      49
 
CCITT Draft Recommendation T.4                      PAGE   9



         000001010010    12      50
         000001010011    12      51
         000000100100    12      52
         000000110111    12      53
         000000111000    12      54
         000000100111    12      55
         000000101000    12      56
         000001011000    12      57
         000001011001    12      58
         000000101011    12      59
         000000101100    12      60
         000001011010    12      61
         000001100110    12      62
         000001100111    12      63
 
CCITT Draft Recommendation T.4                      PAGE  10



         Table 2b. Make Up Black Codes
         Code            Lng     Run
         ---------------------------
         0000001111      10      64
         000011001000    12      128
         000011001001    12      192
         000001011011    12      256
         000000110011    12      320
         000000110100    12      384
         000000110101    12      448
         0000001101100   13      512
         0000001101101   13      576
         0000001001010   13      640
         0000001001011   13      704
         0000001001100   13      768
         0000001001101   13      832
         0000001110010   13      896
         0000001110011   13      960
         0000001110100   13      1024
         0000001110101   13      1088
         0000001110110   13      1152
         0000001110111   13      1216
         0000001010010   13      1280
         0000001010011   13      1344
         0000001010100   13      1408
         0000001010101   13      1472
         0000001011010   13      1536
         0000001011011   13      1600
         0000001100100   13      1664
         0000001100101   13      1728
 
CCITT Draft Recommendation T.4                      PAGE  11



Note: It is recognized that machines exist which accommodate
larger   paper   widths   whilst  maintaining  the  standard
horizontal resolution.  This option has been provided for by
the addition of the Make Up Code Set defined as follows:

     
     
         Table 3. Extended Make Up Codes (Black and White)
         Code            Lng     Run
         ---------------------------
         00000001000     11      1792
         00000001100     11      1856
         00000001101     11      1920
         000000010010    12      1984
         000000010011    12      2048
         000000010100    12      2112
         000000010101    12      2176
         000000010110    12      2240
         000000010111    12      2304
         000000011100    12      2368
         000000011101    12      2432
         000000011110    12      2496
         000000011111    12      2560

     The identification and choice of  either  the  standard
code  table  or the extended code table is to be made in the
pre-message  (Phase  B)  portion   of   the   T.30   control
procedures.

4.2 Two dimensional coding scheme

     The one-dimensional coding scheme defined in 4.1 may be
extended  as an option to a two-dimensional scheme.  This is
the subject of further study.

5.  Modulation and demodulation method

     It is  provisionally  agreed  that  Group  3  apparatus
operating  on  the  general switched telephone network shall
utilize the modulation scrambler,  equalization  and  timing
signals  defined  in Recommendation V.27ter, specifically in
the preamble and 2, 3, 6, 7, 9 and 10.

     The  data  signalling  rates  to  be  used  are   those
recommended  in  Recommendation V.27ter, i.e.  4800 and 2400
bit/s.

Note 1: Some administrations pointed out that it  would  not
be  possible  to  guarantee the service at a data signalling
rate higher than 2400 bit/s.

Note 2: It should be noted  that  there  are  equipments  in
service  using,  inter  alia, other modulation methods.  The
 
CCITT Draft Recommendation T.4                      PAGE  12



arrangement of interworking between equipment conforming  to
Recommendation  T.4 and these existing equipments is subject
to further study.

Note 3: For higher speed operation, such as may be  possible
on  leased circuits, it is provisionally agreed that Group 3
apparatus may utilize the signals specifically defined in 1,
2, 3, 4, 7, 8, 9, 11, and 12 of Recommendation V.29.