Goto Section: 15.118 | 15.121 | Table of Contents

FCC 15.119
Revised as of
Goto Year:1996 | 1998
Sec. 15.119  Closed caption decoder requirements for television 
          receivers.

    (a) Effective July 1, 1993, all TV broadcast receivers with picture 
screens 33 cm (13 in) or larger in diameter shipped in interstate 
commerce, manufactured, assembled, or imported from any foreign country 
into the United States shall comply with the provisions of this section.

    Note: This paragraph places no restriction on the shipping or sale 
of television receivers that were manufactured before July 1, 1993.

    (b) Transmission format. Closed-caption information is transmitted 
on line 21 of field 1 of the vertical blanking interval of television 
signals, in accordance with Sec. 73.682(a)(22) of this chapter.
    (c) Operating modes. The television receiver will employ customer-
selectable modes of operation for TV and Caption. A third mode of 
operation, Text, may be included on an optional basis. The Caption and 
Text Modes may contain data in either of two operating channels, 
referred to in this document as C1 and C2. The television receiver must 
decode both C1 and C2 captioning, and must display the captioning for 
whichever channel the user selects. The TV Mode of operation allows the 
video to be viewed in its original form. The Caption and Text Modes 
define one or more areas (called ``boxes'') on the screen within which 
caption or text characters are displayed.

    Note: For more information regarding Text mode, see ``Television 
Captioning for the Deaf: Signal and Display Specifications'', 
Engineering Report No. E-7709-C, Public Broadcasting Service, dated May 
1980, and ``TeleCaption II Decoder Module Performance Specification'', 
National Captioning Institute, Inc., dated November 1985. These 
documents are available, respectively, from the Public Broadcasting 
Service, 1320 Braddock Place, Alexandria, VA 22314 and from the National 
Captioning Institute, Inc., 5203 Leesburg Pike, Falls Church, VA 22041.

    (d) Screen format. The display area for captioning and text shall 
fall approximately within the safe caption area as defined in paragraph 
(n)(12) of this section. This display area will be further divided into 
15 character rows of equal height and 32 columns of equal width, to 
provide accurate placement of text on the screen. Vertically, the 
display area begins on line 43 and is 195 lines high, ending on line 237 
on an interlaced display. All captioning and text shall fall within 
these established columns and rows. The characters must be displayed 
clearly separated from the video over which they are placed. In 
addition, the user must have the capability to select a black background 
over which the captioned letters are displaced.
    (1) Caption mode. In the Caption Mode, text can appear on up to 4 
rows simultaneously anywhere on the screen within the defined display 
area. In addition, a solid space equal to one column width may be placed 
before the first character and after the last character of each row to 
enhance legibility. The caption area will be transparent anywhere that 
either:
    (i) No standard space character or other character has been 
addressed and no accompanying solid space is needed; or,
    (ii) An accompanying solid space is used and a ``transparent space'' 
special character has been addressed which does not immediately precede 
or follow a displayed character.
    (2) [Reserved]
    (e) Presentation format. In analyzing the presentation of 
characters, it is convenient to think in terms of a non-visible cursor 
which marks the screen position at which the next event in a given mode 
and data channel will occur. The receiver remembers the cursor position 
for each mode even when data are received for a different address in an 
alternate mode or data channel.
    (1) Screen addressing. Two kinds of control codes are used to move 
the cursor to specific screen locations. In Caption Mode, these 
addressing codes will affect both row and column positioning. In Text 
Mode, the codes affect only column positioning. In both modes, the 
addressing codes are optional. Default positions are defined for each 
mode and style when no addressing code is provided.
    (i) The first type of addressing code is the Preamble Address Code 
(PAC). It assigns a row number and one of eight ``indent'' figures. Each 
successive indent moves the cursor four columns to the right (starting 
from the left margin). Thus, an indent of 0 places the

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cursor at Column 1, an indent of 4 sets it at Column 5, etc. The PAC 
indent is non-destructive to displayable characters. It will not affect 
the display to the left of the new cursor position on the indicated row. 
Note that Preamble Address Codes also set initial attributes for the 
displayable characters which follow. See paragraph (h) of this section 
and the Preamble Address Code table.
    (ii) The second type of addressing code is the Tab Offset, which is 
one of three Miscellaneous Control Codes. Tab Offset will move the 
cursor one, two, or three columns to the right. The character cells 
skipped over will be unaffected; displayable characters in these cells, 
if any, will remain intact while empty cells will remain empty, in the 
same manner that a PAC indent is non-destructive.
    (2) [Reserved]
    (f) Caption Mode. There are three styles of presenting text in 
Caption Mode: roll-up, pop-on, and paint-on. Character display varies 
significantly with the style used, but certain rules of character 
erasure are common to all styles. A character can be erased by 
addressing another character to the same screen location or by 
backspacing over the character from a subsequent location on the same 
row. The entire displayed memory will be erased instantly by receipt of 
an Erase Displayed Memory command. Both displayed memory and non-
displayed memory will be entirely erased simultaneously by either: The 
user switching receiver channels or data channels (C1/C2) or fields (F1/
F2) in decoders so equipped; the loss of valid data (see paragraph (j) 
of this section); or selecting non-captioning receiver functions which 
use the display memory of the decoder. Receipt of an End of Caption 
command will cause a displayed caption to become non-displayed (and vice 
versa) without being erased from memory. Changing the receiver to a non-
captioning mode which does not require use of the decoder's display 
memory will leave that memory intact, and the decoder will continue to 
process data as if the caption display were selected.
    (1) Roll-up. Roll-up style captioning is initiated by receipt of one 
of three Miscellaneous Control Codes that determine the maximum number 
of rows displayed simultaneously, either 2, 3 or 4 contiguous rows. 
These are the three Roll-Up Caption commands.
    (i) The bottom row of the display is known as the ``base row''. The 
cursor always remains on the base row. Rows of text roll upwards into 
the contiguous rows immediately above the base row to create a 
``window'' 2 to 4 rows high.
    (ii) The Roll-Up command, in normal practice, will be followed (not 
necessarily immediately) by a Preamble Address Code indicating the base 
row and the horizontal indent position. If no Preamble Address Code is 
received, the base row will default to Row 15 or, if a roll-up caption 
is currently displayed, to the same base row last received, and the 
cursor will be placed at Column 1. If the Preamble Address Code received 
contains a different base row than that of a currently displayed 
caption, the entire window will move intact (and without erasing) to the 
new base row immediately.
    (iii) Each time a Carriage Return is received, the text in the top 
row of the window is erased from memory and from the display or scrolled 
off the top of the window. The remaining rows of text are each rolled up 
into the next highest row in the window, leaving the base row blank and 
ready to accept new text. This roll-up must appear smooth to the user, 
and must take no more than 0.433 second to complete. The cursor is 
automatically placed at Column 1 (pending receipt of a Preamble Address 
Code).
    (iv) Increasing or decreasing the number of roll-up rows instantly 
changes the size of the active display window, appropriately turning on 
or off the display of the top one or two rows. A row which is turned off 
should also be erased from memory.
    (v) Characters are always displayed immediately when received by the 
receiver. Once the cursor reaches the 32nd column position on any row, 
all subsequent characters received prior to a Carriage Return, Preamble 
Address Code, or Backspace will be displayed in that column replacing 
any previous character occupying that address.
    (vi) The cursor moves automatically one column to the right after 
each

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character or Mid-Row Code received. A Backspace will move the cursor one 
column to the left, erasing the character or Mid-Row Code occupying that 
location. (A Backspace received when the cursor is in Column 1 will be 
ignored.)
    (vii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on the row after the Delete to End of Row is acted 
upon, the solid space (if any) for that row should also be erased to 
conform with the following provisions.
    (viii) If a solid space is used for legibility, it should appear 
when the first displayable character (not a transparent space) or Mid-
Row Code is received on a row, not when the Preamble Address Code, if 
any, is given. A row on which there are no displayable characters or 
Mid-Row Codes will not display a solid space, even when rolled up 
between two rows which do display a solid space.
    (ix) If the reception of data for a row is interrupted by data for 
the alternate data channel or for Text Mode, the display of caption text 
will resume from the same cursor position if a Roll-Up Caption command 
is received and no Preamble Address Code is given which would move the 
cursor.
    (x) A roll-up caption remains displayed until one of the standard 
caption erasure techniques is applied. Receipt of a Resume Caption 
Loading command (for pop-on style) or a Resume Direct Captioning command 
(for paint-on style) will not affect a roll-up display. Receipt of a 
Roll-Up Caption command will cause any pop-on or paint-on caption to be 
erased from displayed memory and non-displayed memory.
    (2) Pop-on. Pop-on style captioning is initiated by receipt of a 
Resume Caption Loading command. Subsequent data are loaded into a non-
displayed memory and held there until an End of Caption command is 
received, at which point the non-displayed memory becomes the displayed 
memory and vice versa. (This process is often referred to as ``flipping 
memories'' and does not automatically erase memory.) An End of Caption 
command forces the receiver into pop-on style if no Resume Caption 
Loading command has been received which would do so. The display will be 
capable of 4 full rows, not necessarily contiguous, simultaneous 
anywhere on the screen.
    (i) Preamble Address Codes can be used to move the cursor around the 
screen in random order to place captions on Rows 1 to 15. Carriage 
Returns have no effect on cursor location during caption loading.
    (ii) The cursor moves automatically one column to the right after 
each character or Mid-Row Code received. Receipt of a Backspace will 
move the cursor one column to the left, erasing the character or Mid-Row 
Code occupying that location. (A Backspace received when the cursor is 
in Column 1 will be ignored.) Once the cursor reaches the 32nd column 
position on any row, all subsequent characters received prior to a 
Backspace, an End of Caption, or a Preamble Address Code, will replace 
any previous character at that location.
    (iii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on a row after the Delete to End of Row is acted upon, 
the solid space (if any) for that element should also be erased.
    (iv) If data reception is interrupted during caption loading by data 
for the alternate caption channel or for Text Mode, caption loading will 
resume at the same cursor position if a Resume Caption Loading command 
is received and no Preamble Address Code is given that would move the 
cursor.
    (v) Characters remain in non-displayed memory until an End of 
Caption command flips memories. The caption will be erased without being 
displayed upon receipt of an Erase Non-Displayed Memory command, a Roll-
Up Caption command, or if the user switches receiver channels, data 
channels or fields, or upon the loss of valid data (see paragraph (j) of 
this section).
    (vi) A pop-on caption, once displayed, remains displayed until one 
of the standard caption erasure techniques is

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applied or until a Roll-Up Caption command is received. Characters 
within a displayed pop-on caption will be replaced by receipt of the 
Resume Direct Captioning command and paint-on style techniques (see 
below).
    (3) Paint-on. Paint-on style captioning is initiated by receipt of a 
Resume Direct Captioning command. Subsequent data are addressed 
immediately to displayed memory without need for an End of Caption 
command.
    (i) Preamble Address Codes can be used to move the cursor around the 
screen in random order to display captions on Rows 1 to 15. Carriage 
Returns have no affect on cursor location during direct captioning. The 
cursor moves automatically one column to the right after each character 
or Mid-Row Code is received. Receipt of a Backspace will move the cursor 
one column to the left, erasing the character or Mid-Row Code occupying 
that location. (A Backspace received when the cursor is in Column 1 will 
be ignored.) Once the cursor reaches the 32nd column position on any 
row, all subsequent characters received prior to a Preamble Address Code 
or Backspace will be displayed in that column replacing any previous 
character occupying that location.
    (ii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on the row after the Delete to End of Row is acted 
upon, the solid space (if any) for that element should also be erased.
    (iii) If the reception of data is interrupted during the direct 
captioning by data for the alternate caption channel or for Text Mode, 
the display of caption text will resume at the same cursor position if a 
Resume Direct Captioning command is received and no Preamble Address 
Code is given which would move the cursor.
    (iv) Characters remain displayed until one of the standard caption 
erasure techniques is applied or until a Roll-Up Caption command is 
received. An End of Caption command leaves a paint-on caption fully 
intact in non-displayed memory. In other words, a paint-on style caption 
behaves precisely like a pop-on style caption which has been displayed.
    (g) Character format. Characters are to be displayed on the screen 
within a character ``cell'' which is the height and width of a single 
row and column. The following codes define the displayable character 
set. Television receivers manufactured prior to January 1, 1996 and 
having a character resolution of 5  x  7 dots, or less, may display the 
allowable alternate characters in the character table. A statement must 
be in a prominent location on the box or other package in which the 
receiver is to be marketed, and information must be in the owner's 
manual, indicating the receiver displays closed captioning in upper case 
only.

                           Character Set Table

                           Special Characters

    These require two bytes for each symbol. Each hex code as shown will 
be preceded by a 11h for data channel 1 or by a 19h for data channel 2. 
For example: 19h 37h will place a musical note in data channel 2.

                                                                        
------------------------------------------------------------------------
HEX  Example   Alternate                    Description                 
------------------------------------------------------------------------
30.  TM  See note\1                                                
                       \  Trademark symbol                              
35.    cents              Cents sign                                    
36.  TM. It is left to each individual manufacturer to interpret  
  these symbols in any way that meets the legal needs of the user.      

                           Standard characters

                                                                        
------------------------------------------------------------------------
HEX  Example  Alternate                    Description                  
------------------------------------------------------------------------
20.                      Standard space                                 
21.        !             Exclamation mark                               
22.       ``             Quotation mark                                 
23.                     Pounds (number) sign                           
24.        $             Dollar sign                                    
25.        %             Percentage sign                                

[[Page 644]]

                                                                        
26.        &             Ampersand                                      
27.        '             Apostrophe                                     
28.        (             Open parentheses                               
29.        )             Close parentheses                              
2A.        a          A  Lower-case a with acute accent                 
2B.        +             Plus sign                                      
2C.        ,             Comma                                          
2D.        -             Minus (hyphen) sign                            
2E.        .             Period                                         
2F.        /             Slash                                          
30.        0             Zero                                           
31.        1             One                                            
32.        2             Two                                            
33.        3             Three                                          
34.        4             Four                                           
35.        5             Five                                           
36.        6             Six                                            
37.        7             Seven                                          
38.        8             Eight                                          
39.        9             Nine                                           
3A.        :             Colon                                          
3B.        ;             Semi-colon                                     
3C.        <             Less than sign                                 
3D.        =             Equal sign                                     
3E.        >             Greater than sign                              
3F.        ?             Question mark                                  
40.        @             At sign                                        
41.        A             Upper-case A                                   
42.        B             Upper-case B                                   
43.        C             Upper-case C                                   
44.        D             Upper-case D                                   
45.        E             Upper-case E                                   
46.        F             Upper-case F                                   
47.        G             Upper-case G                                   
48.        H             Upper-case H                                   
49.        I             Upper-case I                                   
4A.        J             Upper-case J                                   
4B.        K             Upper-case K                                   
4C.        L             Upper-case L                                   
4D.        M             Upper-case M                                   
4E.        N             Upper-case N                                   
4F.        O             Upper-case O                                   
50.        P             Upper-case P                                   
51.        Q             Upper-case Q                                   
52.        R             Upper-case R                                   
53.        S             Upper-case S                                   
54.        T             Upper-case T                                   
55.        U             Upper-case U                                   
56.        V             Upper-case V                                   
57.        W             Upper-case W                                   
58.        X             Upper-case X                                   
59.        Y             Upper-case Y                                   
5A.        Z             Upper-case Z                                   
5B.        [             Open bracket                                   
5C.        e          E  Lower-case e with acute accent                 
5D.        ]             Close bracket                                  
5E.        i          I  Lower-case i with acute accent                 
5F.        o          O  Lower-case o with acute accent                 
60.        u          U  Lower-case u with acute accent                 
61.        a          A  Lower-case a                                   
62.        b          B  Lower-case b                                   
63.        c          C  Lower-case c                                   
64.        d          D  Lower-case d                                   
65.        e          E  Lower-case e                                   
66.        f          F  Lower-case f                                   
67.        g          G  Lower-case g                                   
68.        h          H  Lower-case h                                   
69.        i          I  Lower-case i                                   
6A.        j          J  Lower-case j                                   
6B.        k          K  Lower-case k                                   
6C.        l          L  Lower-case l                                   
6D.        m          M  Lower-case m                                   
6E.        n          N  Lower-case n                                   
6F.        o          O  Lower-case o                                   
70.        p          P  Lower-case p                                   
71.        q          Q  Lower-case q                                   
72.        r          R  Lower-case r                                   
73.        s          S  Lower-case s                                   
74.        t          T  Lower-case t                                   
75.        u          U  Lower-case u                                   
76.        v          V  Lower-case v                                   
77.        w          W  Lower-case w                                   
78.        x          X  Lower-case x                                   
79.        y          Y  Lower-case y                                   
7A.        z          Z  Lower-case z                                   
7B.        c          C  Lower-case c with cedilla                      
7C.               Division sign                                  
7D.        N             Upper-case N with tilde                        
7E.        n          N  Lower-case n with tilde                        
7F.                 Solid block                                    
------------------------------------------------------------------------

    (h) Character Attributes--(1) Transmission of Attributes. A 
character may be transmitted with any or all of four attributes: Color, 
italics, underline, and flash. All of these attributes are set by 
control codes included in the received data. An attribute will remain in 
effect until changed by another control code or until the end of the row 
is reached. Each row begins with a control code which sets the color and 
underline attributes. (White non-underlined is the default display 
attribute if no Preamble Address Code is received before the first 
character on an empty row.) Attributes are not affected by transparent 
spaces within a row.
    (i) All Mid-Row Codes and the Flash On command are spacing 
attributes which appear in the display just as if a standard space (20h) 
had been received. Preamble Address Codes are non-spacing and will not 
alter any attributes when used to position the cursor in the midst of a 
row of characters.
    (ii) The color attribute has the highest priority and can only be 
changed by the Mid-Row Code of another color. Italics has the next 
highest priority. If characters with both color and italics are desired, 
the italics Mid-Row Code must follow the color assignment. Any color 
Mid-Row Code will turn off italics. If the least significant bit of a 
Preamble Address Code or of a color or italics Mid-Row Code is a 1 
(high), underlining is turned on. If that bit is a 0 (low), underlining 
is off.
    (iii) The flash attribute is transmitted as a Miscellaneous Control 
Code. The Flash On command will not alter the status of the color, 
italics, or underline attributes. However, any color

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or italics Mid-Row Code will turn off flash.
    (iv) Thus, for example, if a red, italicized, underlined, flashing 
character is desired, the attributes must be received in the following 
order: a red Mid-Row or Preamble Address Code, an italics Mid-Row Code 
with underline bit, and the Flash On command. The character will then be 
preceded by three spaces (two if red was assigned via a Preamble Address 
Code).
    (2) Display of attributes. The underline attribute will be displayed 
by drawing a line beneath the character in the same color as the 
character. The flash attribute will be displayed by causing the 
character to blink from the display at least once per second. The italic 
attribute must be capable of being displayed by either a special italic 
font, or by the modification of the standard font by slanting. The user 
may be given the option to select other methods of italic display as 
well. The support of the color attributes is optional. If the color 
attributes are supported, they will be displayed in the color they have 
been assigned. If color attributes are not supported, the display may be 
in color, but all color changes will be ignored.
    (i) Control codes. There are three different types of control codes 
used to identify the format, location, attributes, and display of 
characters: Preamble Address Codes, Mid-Row Codes, and Miscellaneous 
Control Codes.
    (1) Each control code consists of a pair of bytes which are always 
transmitted together in a single field of line 21 and which are normally 
transmitted twice in succession to help insure correct reception of the 
control instructions. The first of the control code bytes is a non-
printing character in the range 10h to 1Fh. The second byte is always a 
printing character in the range 20h to 7Fh. Any such control code pair 
received which has not been assigned a function is ignored. If the non-
printing character in the pair is in the range 00h to 0Fh, that 
character alone will be ignored and the second character will be treated 
normally.
    (2) If the second byte of a control code pair does not contain odd 
parity (see paragraph (j) of this section), then the pair is ignored. 
The redundant transmission of the pair will be the instruction upon 
which the receiver acts.
    (3) If the first byte of the first transmission of a control code 
pair fails the parity check, then that byte is inserted into the 
currently active memory as a solid block character (7Fh) followed by 
whatever the second byte is. Again, the redundant transmission of the 
pair will be the controlling instruction.
    (4) If the first transmission of a control code pair passes parity, 
it is acted upon within one video frame. If the next frame contains a 
perfect repeat of the same pair, the redundant code is ignored. If, 
however, the next frame contains a different but also valid control code 
pair, this pair, too, will be acted upon (and the receiver will expect a 
repeat of this second pair in the next frame). If the first byte of the 
expected redundant control code pair fails the parity check and the 
second byte is identical to the second byte in the immediately preceding 
pair, then the expected redundant code is ignored. If there are printing 
characters in place of the redundant code, they will be processed 
normally.
    (5) There is provision for decoding a second data channel. The 
second data channel is encoded with the same control codes and 
procedures already described. The first byte of every control code pair 
indicates the data channel (C1/C2) to which the command applies. Control 
codes which do not match the data channel selected by the user, and all 
subsequent data related to that control code, are ignored by the 
receiver.

                              Mid-Row Codes                             
------------------------------------------------------------------------
   Data        Data                                                     
 channel 1   channel 2                Attribute description             
------------------------------------------------------------------------
11  20....      19  20  White.                                          
11  21....      19  21  White Underline.                                
11  22....      19  22  Green.                                          
11  23....      19  23  Green Underline.                                
11  24....      19  24  Blue.                                           
11  25....      19  25  Blue Underline.                                 
11  26....      19  26  Cyan.                                           
11  27....      19  27  Cyan Underline.                                 
11  28....      19  28  Red.                                            
11  29....      19  29  Red Underline.                                  
11  2A....      19  2A  Yellow.                                         
11  2B....      19  2B  Yellow Underline.                               
11  2C....      19  2C  Magenta.                                        
11  2D....      19  2D  Magenta Underline.                              
11  2E....      19  2E  Italics.                                        
11  2F....      19  2F  Italics Underline.                              

[[Page 646]]

                                                                        
------------------------------------------------------------------------


                       Miscellaneous Control Codes                      
------------------------------------------------------------------------
   Data        Data                                                     
 channel 1   channel 2        Mnemonic            Command description   
------------------------------------------------------------------------
14  20....      1C  20  RCL.................  Resume caption loading.   
14  21....      1C  21  BS..................  Backspace.                
14  22....      1C  22  AOF.................  Reserved (formerly Alarm  
                                               Off).                    
14  23....      1C  23  AON.................  Reserved (formerly Alarm  
                                               On).                     
14  24....      1C  24  DER.................  Delete to End of Row.     
14  25....      1C  25  RU2.................  Roll-Up Captions-2 Rows.  
14  26....      1C  26  RU3.................  Roll-Up Captions-3 Rows.  
14  27....      1C  27  RU4.................  Roll-Up Captions-4 Rows.  
14  28....      1C  28  FON.................  Flash On.                 
14  29....      1C  29  RDC.................  Resume Direct Captioning. 
14  2A....      1C  2A  TR..................  Text Restart.             
14  2B....      1C  2B  RTD.................  Resume Text Display.      
14  2C....      1C  2C  EDM.................  Erase Displayed Memory.   
14  2D....      1C  2D  CR..................  Carriage Return.          
14  2E....      1C  2E  ENM.................  Erase Non-Displayed       
                                               Memory.                  
14  2F....      1C  2F  EOC.................  End of Caption (Flip      
                                               Memories).               
17  21....      1F  21  TO1.................  Tab Offset 1 Column.      
17  22....      1F  22  TO2.................  Tab Offset 2 Columns.     
17  23....      1F  23  TO3.................  Tab Offset 3 Columns.     

[[Page 647]]

                                                                        
------------------------------------------------------------------------


                                                                 Preamble Addre
ss Codes                                                                 
-------------------------------------------------------------------------------
-------------------------------------------------------------------------
                                   Row 1   Row 2   Row 3   Row 4   Row 5   Row 
6   Row 7   Row 8   Row 9  Row 10  Row 11  Row 12  Row 13  Row 14  Row 15
-------------------------------------------------------------------------------
-------------------------------------------------------------------------
First byte of code pair:                                                       
                                                                         
    Data Channel 1..............      11      11      12      12      15      1
5      16      16      17      17      10      13      13      14      14
    Data Channel 2..............      19      19      1A      1A      1D      1
D      1E      1E      1F      1F      18      1B      1B      1C      1C
Second byte of code pair:                                                      
                                                                         
    White.......................      40      60      40      60      40      6
0      40      60      40      60      40      40      60      40      60
    White Underline.............      41      61      41      61      41      6
1      41      61      41      61      41      41      61      41      61
    Green.......................      42      62      42      62      42      6
2      42      62      42      62      42      42      62      42      62
    Green Underline.............      43      63      43      63      43      6
3      43      63      43      63      43      43      63      43      63
    Blue........................      44      64      44      64      44      6
4      44      64      44      64      44      44      64      44      64
    Blue Underline..............      45      65      45      65      45      6
5      45      65      45      65      45      45      65      45      65
    Cyan........................      46      66      46      66      46      6
6      46      66      46      66      46      46      66      46      66
    Cyan Underline..............      47      67      47      67      47      6
7      47      67      47      67      47      47      67      47      67
    Red.........................      48      68      48      68      48      6
8      48      68      48      68      48      48      68      48      68
    Red Underline...............      49      69      49      69      49      6
9      49      69      49      69      49      49      69      49      69
    Yellow......................      4A      6A      4A      6A      4A      6
A      4A      6A      4A      6A      4A      4A      6A      4A      6A
    Yellow Underline............      4B      6B      4B      6B      4B      6
B      4B      6B      4B      6B      4B      4B      68      4B      6B
    Magenta.....................      4C      6C      4C      6C      4C      6
C      4C      6C      4C      6C      4C      4C      6C      4C      6C
    Magenta Underline...........      4D      6D      4D      6D      4D      6
D      4D      6D      4D      6D      4D      4D      6D      4D      6D
    White Italics...............      4E      6E      4E      6E      4E      6
E      4E      6E      4E      6E      4E      4E      6E      4E      6E
    White Italics Underline.....      4F      6F      4F      6F      4F      6
F      4F      6F      4F      6F      4F      4F      6F      4F      6F
    Indent 0....................      50      70      50      70      50      7
0      50      70      50      70      50      50      70      50      70
    Indent 0 Underline..........      51      71      51      71      51      7
1      51      71      51      71      51      51      71      51      71
    Indent 4....................      52      72      52      72      52      7
2      52      72      52      72      52      52      72      52      72
    Indent 4 Underline..........      53      73      53      73      53      7
3      53      73      53      73      53      53      73      53      73
    Indent 8....................      54      74      54      74      54      7
4      54      74      54      74      54      54      74      54      74
    Indent 8 Underline..........      55      75      55      75      55      7
5      55      75      55      75      55      55      75      55      75
    Indent 12...................      56      76      56      76      56      7
6      56      76      56      76      56      56      76      56      76
    Indent 12 Underline.........      57      77      57      77      57      7
7      57      77      57      77      57      57      77      57      77
    Indent 16...................      58      78      58      78      58      7
8      58      78      58      78      58      58      78      58      78
    Indent 16 Underline.........      59      79      59      79      59      7
9      59      79      59      79      59      59      79      59      79
    Indent 20...................      5A      7A      5A      7A      5A      7
A      5A      7A      5A      7A      5A      5A      7A      5A      7A
    Indent 20 Underline.........      5B      7B      5B      7B      5B      7
B      5B      7B      5B      7B      5B      5B      7B      5B      7B
    Indent 24...................      5C      7C      5C      7C      5C      7
C      5C      7C      5C      7C      5C      5C      7C      5C      7C
    Indent 24 Underline.........      5D      7D      5D      7D      5D      7
D      5D      7D      5D      7D      5D      5D      7D      5D      7D
    Indent 28...................      5E      7E      5E      7E      5E      7
E      5E      7E      5E      7E      5E      5E      7E      5E      7E
    Indent 28 Underline.........      5F      7F      5F      7F      5F      7
F      5F      7F      5F      7F      5F      5F      7F      5F      7F
-------------------------------------------------------------------------------
-------------------------------------------------------------------------
Note: All indent codes (second byte equals 50h-5fh, 70th-7fh) assign white as t
he color attribute.                                                      

[[Page 648]]

                                                                               
                                                                         

    (j) Data rejection. The receiver should provide an effective 
procedure to verify data. A receiver will reject data if the data is 
invalid, or if the data is directed to the data channel or field not 
selected by the user. Invalid data is any data that fails to pass a 
check for odd parity, or which, having passed the parity check, is 
assigned no function.
    (1) If a print character fails to pass a check for parity, a solid 
block (7Fh) should be displayed in place of the failed character. In 
addition, valid data can be corrupted in many ways and may not be 
suitable for display. For example, repeated fields, skipped fields and 
altered field sequences are all possible from consumer video equipment 
and might present meaningless captions.
    (2) The receiver will ignore data rejected due to being directed to 
a deselected field or channel. However, this will not cause the display 
to be disabled.
    (k) Automatic display enable/disable. The receiver shall provide an 
automatic enable/disable capability to prevent the display of invalid or 
incomplete data, when the user selects the Caption Mode. The display 
should automatically become enable after the receiver verifies the data 
as described in paragraph (j) of this section. The display will be 
automatically disabled when there is a sustained detection of invalid 
data. The display will be re-enabled when the data verification process 
has been satisfied once again.
    (l) Compatibility with Cable Security Systems. Certain cable 
television security techniques, such as signal encryption and copy 
protection, can alter the television signal so that some methods of 
finding line 21 will not work. In particular, counting of lines or 
timing from the start of the vertical blanking interval may cause 
problems. Caption decoding circuitry must function properly when 
receiving signals from cable security systems that were designed and 
marketed prior to April 5, 1991. Further information concerning such 
systems is available from the National Cable Television Association, 
Inc., Washington, DC, and from the Electronic Industries Association, 
Washington, DC.
    (m) Labelling and consumer information requirements. The box or 
other package in which the individual television receiver is to be 
marketed shall carry a statement in a prominent location, visible to the 
buyer before purchase, which reads as follows:

    This television receiver provides display of television closed 
captioning in accordance with Sec. 15.119 of the FCC rules.


Receivers that do not support color attributes or text mode, as well as 
receivers that display only upper-case characters pursuant to paragraph 
(g) of this section, must include with the statement, and in the owner's 
manual, language indicating that those features are not supported.
    (n) Glossary of terms. The following terms are used to describe 
caption decoder specifications:
    (1) Base row: The bottom row of a roll-up display. The cursor always 
remains on the base row. Rows of text roll upwards into the contiguous 
rows immediately above the base row.
    (2) Box: The area surrounding the active character display. In Text 
Mode, the box is the entire screen area defined for display, whether or 
not displayable characters appear. In Caption Mode, the box is 
dynamically redefined by each caption and each element of displayable 
characters within a caption. The box (or boxes, in the case of a 
multiple-element caption) includes all the cells of the displayed 
characters, the non-transparent spaces between them, and one cell at the 
beginning and end of each row within a caption element in those decoders 
that use a solid space to improve legibility.
    (3) Caption window: The invisible rectangle which defines the top 
and bottom limits of a roll-up caption. The window can be 2 to 4 rows 
high. The lowest row of the window is called the base row.
    (4) Cell: The discrete screen area in which each displayable 
character or space may appear. A cell is one row high and one column 
wide.
    (5) Column: One of 32 vertical divisions of the screen, each of 
equal width, extending approximately across the full width of the safe 
caption area as defined in paragraph (n)(12) of this section. Two 
additional columns, one

[[Page 649]]

at the left of the screen and one at the right, may be defined for the 
appearance of a box in those decoders which use a solid space to improve 
legibility, but no displayable characters may appear in those additional 
columns. For reference, columns may be numbered 0 to 33, with columns 1 
to 32 reserved for displayable characters.
    (6) Displayable character: Any letter, number or symbol which is 
defined for on-screen display, plus the 20h space.
    (7) Display disable: To turn off the display of captions or text 
(and accompanying background) at the receiver, rather than through codes 
transmitted on line 21 which unconditionally erase the display. The 
receiver may disable the display because the user selects an alternate 
mode, e.g., TV Mode, or because no valid line 21 data is present.
    (8) Display enable: To allow the display of captions or text when 
they are transmitted on line 21 and received as valid data. For display 
to be enabled, the user must have selected Caption Mode or Text Mode, 
and valid data for the selected mode must be present on line 21.
    (9) Element: In a pop-on or paint-on style caption, each contiguous 
area of cells containing displayable characters and non-transparent 
spaces between those characters. A single caption may have multiple 
elements. An element is not necessarily a perfect rectangle, but may 
include rows of differing widths.
    (10) Erase Display: In Caption Mode, to clear the screen of all 
characters (and accompanying background) in response to codes 
transmitted on line 21. (The caption service provider can accomplish the 
erasure either by sending an Erase Displayed Memory command or by 
sending an Erase Non-Displayed Memory command followed by an End of 
Caption command, effectively making a blank caption ``appear''.) Display 
can also be erased by the receiver when the caption memory erasure 
conditions are met, such as the user changing TV channels.
    (11) Row: One of 15 horizontal divisions of the screen, extending 
across the full height of the safe caption area as defined in paragraph 
(n)(12) of this section.
    (12) Safe caption area: The area of the television picture within 
which captioning and text shall be displayed to ensure visibility of the 
information on the majority of home television receivers. The safe 
caption area is specified as shown in the following figure:

[[Page 650]]

[GRAPHIC] [TIFF OMITTED] TC03JN91.009


    The dimensions of the above figure shall be as follows:

                                                                        
------------------------------------------------------------------------
                                                             Percent of 
                                                             television 
          Label                      Dimensions                picture  
                                                               height   
------------------------------------------------------------------------
A                         Television picture height.......        100.0 
B                         Television picture width........        133.33
C                         Height of safe caption area.....         80.0 
D                         Width of safe caption area......        106.67
E                         Vertical position of safe                10.0 
                           caption area.                                
F                         Horizontal position of safe              13.33
                           caption area.                                
------------------------------------------------------------------------

    (13) Special characters: Displayable characters (except for 
``transparent space'') which require a two-byte sequence of one non-
printing and one printing character. The non-printing byte varies 
depending on the data channel. Regular characters require unique one-
byte codes which are the same in either data channel.
    (14) Text: When written with an upper-case ``T'', refers to the Text 
Mode. When written with a lower-case ``t'', refers to any combination of 
displayable characters.
    (15) Transparent space: Transmitted as a special character, it is a 
one-column-wide space behind which program video is always visible 
(except when a transparent space immediately precedes or follows a 
displayable character and solid box is needed to make that character 
legible).
[ 56 FR 27201 , June 13, 1991, as amended at  57 FR 19094 , May 4, 1992;  58 FR 44893 , Aug. 25, 1993]


Goto Section: 15.118 | 15.121

Goto Year: 1996 | 1998
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