§ 79.101   Closed caption decoder requirements for analog television receivers.

   (a)(1) Effective July 1, 1993, all television 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  to paragraph (a)(1): This paragraph places no restriction on the
   shipping or sale of television receivers that were manufactured before July
   1, 1993.

   (2) Effective January 1, 2014, all television broadcast receivers shipped in
   interstate commerce, manufactured, assembled, or imported from any foreign
   country into the United States shall comply with the provisions of this
   section, if technically feasible, except that television broadcast receivers
   that use a picture screen less than 13 inches in size must comply with the
   provisions  of this section only if doing so is achievable pursuant to
   § 79.103(b)(3).

   Note to paragraph (a)(2): This paragraph places no restrictions on the
   importing, shipping, or sale of television receivers that were manufactured
   before January 1, 2014.

   (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 § 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 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
   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 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 × 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    ®    See  note^1 Registered mark symbol
    31    �°                Degree sign
    32   1/2               1/2
    33    ¿                Inverse query
    34   ^TM   See  note^1 Trademark symbol
    35    ¢                Cents sign
    36    £                Pounds Sterling sign
    37    ♪                Music note
    38    à         A      Lower-case a with grave accent
    39                     Transparent space
    3A    è         E      Lower-case e with grave accent
    3B    â         A      Lower-case a with circumflex
    3C    ê         E      Lower-case e with circumflex
    3D    î         I      Lower-case i with circumflex
    3E    ô         O      Lower-case o with circumflex
    3F    û         U      Lower-case u with circumflex

   ^1Note: The registered and trademark symbols are used to satisfy certain
   legal requirements. There are various legal ways in which these symbols may
   be drawn or displayed. For example, the trademark symbol may be drawn with
   the “T” next to the “M” or over the “M”. It is preferred that the trademark
   symbol  be  superscripted, i.e., XYZ^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
    26    &              Ampersand
    27    '              Apostrophe
    28    (              Open parentheses
    29    )              Close parentheses
    2A    á        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    é        E     Lower-case e with acute accent
    5D    ]              Close bracket
    5E    í        I     Lower-case i with acute accent
    5F    ó        O     Lower-case o with acute accent
    60    ú        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    ç        C     Lower-case c with cedilla
    7C   ÷               Division sign
    7D    Ñ              Upper-case N with tilde
    7E    ñ        Ñ     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 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 channel 1 Data 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.

   Miscellaneous Control Codes
   Data channel 1 Data channel 2 Mne-
   monic 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.

   Preamble Address 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 15 16 16 17 17 10 13 13 14 14
   Data Channel 2 19 19 1A 1A 1D 1D 1E 1E 1F 1F 18 1B 1B 1C 1C
   Second byte of code pair:
   White 40 60 40 60 40 60 40 60 40 60 40 40 60 40 60
   White Underline 41 61 41 61 41 61 41 61 41 61 41 41 61 41 61
   Green 42 62 42 62 42 62 42 62 42 62 42 42 62 42 62
   Green Underline 43 63 43 63 43 63 43 63 43 63 43 43 63 43 63
   Blue 44 64 44 64 44 64 44 64 44 64 44 44 64 44 64
   Blue Underline 45 65 45 65 45 65 45 65 45 65 45 45 65 45 65
   Cyan 46 66 46 66 46 66 46 66 46 66 46 46 66 46 66
   Cyan Underline 47 67 47 67 47 67 47 67 47 67 47 47 67 47 67
   Red 48 68 48 68 48 68 48 68 48 68 48 48 68 48 68
   Red Underline 49 69 49 69 49 69 49 69 49 69 49 49 69 49 69
   Yellow 4A 6A 4A 6A 4A 6A 4A 6A 4A 6A 4A 4A 6A 4A 6A
   Yellow Underline 4B 6B 4B 6B 4B 6B 4B 6B 4B 6B 4B 4B 68 4B 6B
   Magenta 4C 6C 4C 6C 4C 6C 4C 6C 4C 6C 4C 4C 6C 4C 6C
   Magenta Underline 4D 6D 4D 6D 4D 6D 4D 6D 4D 6D 4D 4D 6D 4D 6D
   White Italics 4E 6E 4E 6E 4E 6E 4E 6E 4E 6E 4E 4E 6E 4E 6E
   White Italics Underline 4F 6F 4F 6F 4F 6F 4F 6F 4F 6F 4F 4F 6F 4F 6F
   Indent 0 50 70 50 70 50 70 50 70 50 70 50 50 70 50 70
   Indent 0 Underline 51 71 51 71 51 71 51 71 51 71 51 51 71 51 71
   Indent 4 52 72 52 72 52 72 52 72 52 72 52 52 72 52 72
   Indent 4 Underline 53 73 53 73 53 73 53 73 53 73 53 53 73 53 73
   Indent 8 54 74 54 74 54 74 54 74 54 74 54 54 74 54 74
   Indent 8 Underline 55 75 55 75 55 75 55 75 55 75 55 55 75 55 75
   Indent 12 56 76 56 76 56 76 56 76 56 76 56 56 76 56 76
   Indent 12 Underline 57 77 57 77 57 77 57 77 57 77 57 57 77 57 77
   Indent 16 58 78 58 78 58 78 58 78 58 78 58 58 78 58 78
   Indent 16 Underline 59 79 59 79 59 79 59 79 59 79 59 59 79 59 79
   Indent 20 5A 7A 5A 7A 5A 7A 5A 7A 5A 7A 5A 5A 7A 5A 7A
   Indent 20 Underline 5B 7B 5B 7B 5B 7B 5B 7B 5B 7B 5B 5B 7B 5B 7B
   Indent 24 5C 7C 5C 7C 5C 7C 5C 7C 5C 7C 5C 5C 7C 5C 7C
   Indent 24 Underline 5D 7D 5D 7D 5D 7D 5D 7D 5D 7D 5D 5D 7D 5D 7D
   Indent 28 5E 7E 5E 7E 5E 7E 5E 7E 5E 7E 5E 5E 7E 5E 7E
   Indent 28 Underline 5F 7F 5F 7F 5F 7F 5F 7F 5F 7F 5F 5F 7F 5F 7F

   Note: All indent codes (second byte equals 50h-5fh, 70th-7fh) assign white
   as the color attribute.

   (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) [Reserved]

   (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 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:
   eCFR graphic ec03jn91.009.gif

   View or download PDF

   The dimensions of the above figure shall be as follows:
   Label Dimensions Percent of television 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 caption area 10.0
   F Horizontal position of safe caption area 13.33

   (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. Redesignated and amended at  77 FR 19515 , 19518, Mar.
   30, 2012;  78 FR 39627 , July 2, 2013;  78 FR 77251 , Dec. 20, 2013]

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