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RFC 0841

 
 
 

Specification for message format for Computer Based Message Systems

Part 3 of 4, p. 70 to 99
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prevText      Top       Page 70 
                                 APPENDIX B
               DATA ELEMENTS -- IMPLEMENTORS' MASTER REFERENCE




           The appendix defines all of the data elements in the message
      format  specification,  for  reference  use  by implementors.  It
      contains no new information but rather consolidates the syntactic
      information from Section 4.3.

           Each data element description has the following form.


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



      Data Element        (Compliance)   identifier   identifier
          Name            ( Category )    octet         octet 
                                               16            8

                Constructive class (primitive or constructor)

                Description of the syntax of the data element.



                +---//---+
                |        |     Diagram representing data element
                +---//---+





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

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      ASCII-String             (BASIC)        02        002 
                                                16         8
                primitive

                This data element contains a series of ASCII characters
                 [NatB-80],   each  character  right-justified  in  one
                octet.    For  7-bit   ASCII   characters,   the   most
                significant bit of each octet must be 0.

                Note:  The  ASCII  code  table  can be extended through
                standardized techniques [NatB-75]  to  introduce  addi-
                tional  7-bit  or  8-bit  characters or additional code
                tables.


                 +--------+---//---+----//-----+
                 |P0000010|Lxxxxxxx|ASCII chars|
                 +--------+---//---+----//-----+

      Bit-String               (OPTIONAL)     43        103 
                                                16         8
                primitive

                This data element contains a series of bits.   It  uses
                the  Qualifier  data  element  component  to record the
                number  of  bits  of  padding  (as  an  8-bit  unsigned
                integer)  needed  to  fill  the final octet of the Data
                Element Contents to an  even  octet  boundary.    These
                padding bits have no meaning and occur in the low order
                bits  of  the  final  octet.   The valid values for the
                Qualifier component are 0 through 7.    The  number  of
                bits  in  the  Data Element Contents is calculated from
                the following formula.


                8   *   number of octets   -   value of
                        in the Data            Qualifier component
                        Element Contents


                 +--------+---//---+---//---+---//---+
                 |P1000011|Lxxxxxxx|Qxxxxxxx|  bits  |
                 +--------+---//---+---//---+---//---+

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      Boolean                  (OPTIONAL)     08        010 
                                                16         8
                primitive

                This  data  element  contains  one octet whose value is
                either true or false.  False is represented by all bits
                being 0; true  is  represented  by  all  bits  being  1
                (although  any  non-zero value should be interpreted as
                true).


                 +--------+---//---+--------+
                 |P0001000|Lxxxxxxx| T or F |
                 +--------+---//---+--------+

      Compressed               (OPTIONAL)     46        106 
                                                16         8
                constructor

                This  data  element  must  contain  a  Bit-String  data
                element.    It  is  used to represent any data that has
                been  compressed;  it  may   be   used   wherever   its
                uncompressed  contents  may  appear.   A Qualifier data
                component appears in each Compressed data  element;  it
                contains a compression identifier (CID) to identify the
                compression  algorithm used.  (See Section 4.3.5.)  The
                Data Element  Contents  contains  the  product  of  the
                compression process.


                 +--------+---//---+---//---+--------//--------+
                 |P1000110|Lxxxxxxx|Qxxxxxxx|Bit-String Element|
                 +--------+---//---+---//---+--------//--------+


      Date                     (BASIC)        28        050 
                                                16       8
                constructor

                This   data   element  contains  an  ASCII-String  data
                element, which is a representation of a date  and  time
                formatted  in  accordance  with  FIPS PUBS 4 [NatB-68],
                58 [NatB-79a], and 59 [NatB-79b].  The use of time  and
                time  zone is optional.  It is recommended that numeric
                offsets be used  to  indicate  time  zone  rather  than
                alphabetic abbreviations.


                 +--------+---//---+------//------+
                 |P0101000|Lxxxxxxx| ASCII-String |
                 +--------+---//---+------//------+

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      Encrypted                (OPTIONAL)     47        107 
                                                16         8
                constructor

                This  data  element  must  contain a Bit-String.  It is
                used to represent any data that has been encrypted;  it
                may  be  used  wherever  its  unencrypted  contents may
                appear.  A Qualifier data  component  appears  in  each
                Encrypted  data  element;  it  contains  an  encryption
                identifier (EID) identifying the  encryption  algorithm
                used.  (See Section 4.3.4 for further discussion.)  The
                Data  Element Contents is the product of the encryption
                process.


                 +--------+---//---+---//---+--------//--------+
                 |P1000111|Lxxxxxxx|Qxxxxxxx|Bit-String Element|
                 +--------+---//---+---//---+--------//--------+

      End-of-Constructor       (BASIC)        01        001 
                                                16         8
                primitive

                This data element terminates the Data Element  Contents
                in  a  constructor  data  element  that  has indefinite
                length.  This data element has no  Contents  component.
                (Use of this element is described in Section 4.2.2.1.)


                 +--------+---//---+
                 |P0000001|Lxxxxxxx|
                 +--------+---//---+

      Extension                (OPTIONAL)     7E        176 
                                                16         8
                either

                This  data  element  is  used  to  extend the number of
                available  data  elements  beyond  the  128  that   are
                possible   using  a  7-bit  identifier.    A  Qualifier
                component extends the encoding space  for  identifiers.
                (Extension and Vendor-Defined have the same syntax.)


                 +--------+---//---+---//---+---//---+
                 |P1111110|Lxxxxxxx|Qxxxxxxx|Anything|
                 +--------+---//---+---//---+---//---+

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      Field                    (BASIC)        4C        114 
                                                16         8
                constructor

                This   data  element  uses  a  Qualifier  data  element
                component.  The Qualifier component  contains  a  Field
                Identifier  (FID)  indicating  which  specific field is
                being represented.   (See  Section  4.3.2  for  further
                discussion.)


                 +--------+---//---+---//---+---//---+
                 |P1001100|Lxxxxxxx|Qxxxxxxx|elements|
                 +--------+---//---+---//---+---//---+

      Integer                  (OPTIONAL)     20        040 
                                                16         8
                primitive

                This  data element contains a 2's complement integer of
                variable  length,  high-order  octet  first.    It   is
                recommended  that the data element contents be either 2
                or 4 octets long whenever possible.


                 +--------+---//---+---//---+
                 |P0100000|Lxxxxxxx| Integer|
                 +--------+---//---+---//---+

      Message                  (BASIC)        4D        115 
                                                16         8
                constructor

                This data element may contain  Field  or  Message  data
                elements.    Its Qualifier component contains a Message
                type (MID) indicating the type of the  message.    (See
                Section  4.3.6  for  further  discussion.)  (The MID is
                completely different from the message identifier in the
                Message-ID field and should not be confused with it.)


                 +--------+---//---+---//---+
                 |P1001101|Lxxxxxxx|Qxxxxxxx|
                 +--------+---//---+---//---+

                 +--------//---------//---------//---------//--------+
                 | Field, Message, Encrypted, or Compressed Elements |
                 +--------//---------//---------//---------//--------+

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      No-Op                    (OPTIONAL)     00        000 
                                                16         8
                primitive

                This data element does nothing.  No-Op is used whenever
                it  is  necessary  to include a data element that means
                "no operation."  It is a short placeholder.


                 +--------+---//---+
                 |P0000000|Lxxxxxxx|
                 +--------+---//---+

      Padding                  (OPTIONAL)     21        041 
                                                16         8
                primitive

                This data element is used to fill any number of octets.
                The contents of a Padding  element  are  undefined  and
                convey no information.


                 +--------+---//---+---//---+
                 |P0100001|Lxxxxxxx|anything|
                 +--------+---//---+---//---+

      Property-List            (OPTIONAL)     24        044 
                                                16         8
                constructor

                This  data  element  contains a series of Property data
                elements to be associated with another data element.


                 +--------+---//---+-------//--------+
                 |P0100100|Lxxxxxxx|Property Elements|
                 +--------+---//---+-------//--------+

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      Property                 (OPTIONAL)     45        105 
                                                16         8
                constructor

                This   data  element  uses  a  Qualifier  data  element
                component.      The   Qualifier   component    contains
                a  Property-Identifier (PID) to indicate which specific
                property  is being represented.  (See Section 4.3.3 for
                further discussion.)


                 +--------+---//---+---//---+---//---+
                 |P1000101|Lxxxxxxx|Qxxxxxxx|elements|
                 +--------+---//---+---//---+---//---+

      Sequence                 (OPTIONAL)     0A        012 
                                                16         8
                constructor

                This data element contains any series of data elements.
                Sequence differs from Set in  that  the  data  elements
                making  up the Data Element Contents must be considered
                as an ordered sequence (according  to  their  order  of
                appearance in the sequence.)


                 +--------+---//---+---//---+
                 |P0001010|Lxxxxxxx|elements|
                 +--------+---//---+---//---+

      Set                      (OPTIONAL)     0B        013 
                                                16         8
                constructor

                This  data element contains any series of data elements
                with no ordering of the elements  implied.    (Sequence
                provides   an  ordered  series.)    Although  the  data
                elements  contained   in   a   Set   must   be   stored
                sequentially, the order in which they are stored is not
                defined and not processed.


                 +--------+---//---+---//---+
                 |P0001011|Lxxxxxxx|elements|
                 +--------+---//---+---//---+

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      Unique-ID                (OPTIONAL)     09        011 
                                                16         8
                constructor

                This  data element is a unique identifier.  It need not
                be human-readable.  The Data Element Contents may be an
                ASCII-String, a Bit-String, or an Integer.


                 +--------+---//---+---//---+
                 |P0001001|Lxxxxxxx| element|
                 +--------+---//---+---//---+

      Vendor-Defined           (OPTIONAL)     7F        177 
                                                16         8
                either

                This data element is used to  represent  vendor-defined
                data  elements.    A  Qualifier  component  extends the
                encoding  space  for  identifiers.      The   Qualifier
                component  is  not  guaranteed  to  be unique among all
                interconnected  systems.     This   data   element   is
                interpreted   according   to  prior  agreement  between
                systems.  (Extension and Vendor-Defined  data  elements
                have the same syntax.)


                 +--------+---//---+---//---+---//---+
                 |P1111111|Lxxxxxxx|Qxxxxxxx|Anything|
                 +--------+---//---+---//---+---//---+

Top       Page 78 
                                 APPENDIX C
                       DATA ELEMENT IDENTIFIER OCTETS




      Identifier  Identifier  Data Element Name

      00          000         No-Op
      01          001         End-of-Constructor
      02          002         ASCII-String
      08          010         Boolean
      09          011         Unique-ID
      0A          012         Sequence
      0B          013         Set
      20          040         Integer
      21          041         Padding
      24          044         Property-List
      28          050         Date
      43          103         Bit-String
      45          105         Property
      46          106         Compressed
      47          107         Encrypted
      4C          114         Field
      4D          115         Message
      7E          176         Extension
      7F          177         Vendor-Defined

Top       Page 79 
                                 APPENDIX D
              SUMMARY OF MESSAGE FIELDS BY COMPLIANCE CATEGORY




           This  appendix  is  for  reference  use.  It contains no new
      information, but rather abstracts from that presented in  Section
      3.1.

           This  appendix  contains  the  message  field names arranged
      alphabetically within compliance category.   (Appendix  E  orders
      the  field  names  within  functional  category.)  Complete field
      definitions appear in Appendix A.

           Required fields must appear in a message.  Basic fields must
      be recognized and processed by all CBMS systems.  Optional fields
      need not be supported by  a  CBMS  but,  if  supported,  must  be
      processed according to the meanings defined by the message format
      specification.



      D.1  REQUIRED Fields


      From
      Posted-Date
      To



      D.2  BASIC Fields


      Cc
      Reply-To
      Subject
      Text



      D.3  OPTIONAL Fields


      Attachments
      Author
      Bcc
      Circulate-Next
      Circulate-To
      Comments

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      Date
      End-Date
      In-Reply-To
      Keywords
      Message-Class
      Message-ID
      Obsoletes
      Originator-Serial-Number
      Precedence
      Received-Date
      Received-From
      References
      Reissue-Type
      Sender
      Start-Date
      Warning-Date

Top       Page 81 
                                 APPENDIX E
                  SUMMARY OF MESSAGE SEMANTICS BY FUNCTION




           This  appendix  is  for  reference  use.  It contains no new
      information, but rather abstracts from that presented in  Section
      3.1.

           This  appendix  contains  the  message  field names arranged
      alphabetically within functional class.  (Appendix D  orders  the
      field names within compliance class.)  Complete field definitions
      appear in Appendix A.



      E.1  Circulation


      Circulate-Next
      Circulate-To



      E.2  Cross-Referencing


      In-Reply-To
      Message-ID
      Obsoletes
      Originator-Serial-Number
      References



      E.3  Life Spans


      End-Date
      Start-Date
      Warning-Date



      E.4  Delivery System


      Received-Date
      Received-From

Top       Page 82 
      E.5  Miscellaneous Fields Used Generally


      Attachments
      Comments
      Keywords
      Message-Class
      Precedence
      Subject
      Text



      E.6  Reply Generation


      Reply-To



      E.7  Reissuing


      Reissue-Type



      E.8  Sending (Normal Transmission)


      Author
      Bcc
      Cc
      Date
      From
      Posted-Date
      Sender
      To

Top       Page 83 
                                 APPENDIX F
                       SUMMARY OF DATA ELEMENT SYNTAX




           This  appendix summarizes data element syntax by diagramming
      the components of data elements.  Detailed presentation  of  data
      element syntax appears in Section 4.3.1.

           In  these  diagrams,  required  components of a data element
      appear as follows.  (The double border signifies "required.")


                +========+        +===//===+
                |        |        |        |
                +========+        +===//===+
                always one        one or more
                octet long        octets long


           Optional components of  data  elements  are  represented  as
      follows.  (The single border signifies "not required.")


                +--------+        +---//---+
                |        |        |        |
                +--------+        +---//---+
                always one        one or more
                octet long        octets long


           The  first  octet in a data element is the identifier octet.
      In diagrams of data elements, all eight bits  of  the  identifier
      octet  are  always  shown.  Bits with fixed values show the fixed
      values as 1s and 0s.  Bits with variable values are shown as  x's
      and y's.

           The  first  bit  in  an  identifier octet is the P-bit.  Its
      value indicates whether a data element contains a property  list.
      (A  P-bit  value of 1 indicates the presence of a property list.)
      The remaining seven bits contain the rest of the identifier.

           Other octets in  a  data  element  belong  to  one  of  four
      classes:    Length  Code, Qualifier, Property-List, and Contents.
      In diagrams of syntax the data  element  components  are  labeled
      according to their class.

Top       Page 84 
           Component Class             Label

          Length code                  Length
          Qualifier                    Qual
          Property-List                P-List
          Contents                     Contents


           Data elements must follow this form.


                +========+===//===+---//---+---//---+---//---+
                |Pxxxxxxx| Length |  Qual  | P-List |contents|
                +========+===//===+---//---+---//---+---//---+


      The  value  of the Length component is the total number of octets
      following the length code octet in the data element.

Top       Page 85 
                                 APPENDIX G
               SUMMARY OF DATA ELEMENTS BY COMPLIANCE CATEGORY




           Compliance  categories  for syntactic elements are basic and
      optional.  Every CBMS is required to recognize and process  basic
      elements.    A  CBMS is not required to process optional elements
      although many are strongly recommended by the semantics.

           This appendix  summarizes  data  elements  by  listing  them
      according to their compliance category.



      G.1  BASIC Data Elements


      ASCII-String             (primitive)    02        002 
                                                16         8
      Date                     (constructor)  28        050 
                                                16         8
      End-Of-Constructor       (primitive)    01        001 
                                                16         8
      Field                    (constructor)  4C        114 
                                                16         8
      Message                  (constructor)  4D        115 
                                                16         8


      G.2  OPTIONAL Data Elements


      Bit-String               (primitive)    43        103 
                                                16         8
      Boolean                  (primitive)    08        010 
                                                16         8
      Compressed               (constructor)  46        106 
                                                16         8
      Encrypted                (constructor)  47        107 
                                                16         8
      Extension                (either)       7E        176 
                                                16         8
      Integer                  (primitive)    20        040 
                                                16         8
      No-Op                    (primitive)    00        000 
                                                16         8
      Padding                  (primitive)    21        041 
                                                16         8

Top       Page 86 
      Property                 (constructor)  45        105 
                                                16         8
      Property-List            (constructor)  24        044 
                                                16         8
      Sequence                 (constructor)  0A        012 
                                                16         8
      Set                      (constructor)  0B        013 
                                                16         8
      Unique-ID                (constructor)  09        011 
                                                16         8
      Vendor-Defined           (either)       7F        377 
                                                16         8

Top       Page 87 
                                 APPENDIX H
                                  EXAMPLES




           This  appendix presents at least one example for each of the
      data elements defined in this message format specification.    In
      these examples, identifier octets are represented in binary form.
      All  other  numbers  are presented in hexadecimal.  ASCII strings
      are shown as characters rather  than  their  numerical  represen-
      tation.    Although  this  message  format specification does not
      define the syntax of names and addresses, message originators and
      recipients are identified by their names.  This  does  not  imply
      anything  about  how naming and addressing can or should be done;
      it is simply a convenient way to identify message originators and
      recipients in these examples.



      H.1  Primitive Data Elements


           This section contains an example of each  of  the  primitive
      data  elements.   Each example contains a short explanation and a
      series of octets.

           No-Op data element:


           +--------+--------+
           |00000000|00000000|
           +--------+--------+





           End-of-Constructor data element:


           +--------+--------+
           |00000001|00000000|
           +--------+--------+

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           Boolean data element whose value is true:


           +--------+--------+--------+
           |00001000|00000001|11111111|
           +--------+--------+--------+





           Integer  data  element  containing five octets of data.  Its
      value is 4,294,967,296 (decimal):


           +--------+--------+--------+--------+--------+
           |00100000|  0   5 |  0   1    0   0    0   0
           +--------+--------+--------+--------+--------+

                    +--------+--------+
                       0   0    0   0 |
                    +--------+--------+





           Padding data element containing  three  octets  of  padding.
      The values of those three octets are meaningless:


           +--------+--------+--------+--------+--------+
           |00100001|  0   3 |  F   F    F   F    F   F |
           +--------+--------+--------+--------+--------+





           ASCII-String  data  element containing nine characters.  Its
      value is "Hi There.":


           +--------+--------+---- ----+
           |00000010|  0   9 |Hi There.|
           +--------+--------+---- ----+

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           Bit-String data element containing 44 bits of data (((7-1) x
      8)  - 4).  Six octets are used to hold those 44 bits.  The last 4
      bits in the final octet are padding and are therefore ignored.


           Bit-String  Length   Spare
           +--------+--------+--------+--------+--------+
           |01000011|  0   7 |  0   4 |  0   A    3   B
           +--------+--------+--------+--------+--------+

                    +--------+--------+--------+--------+
                       5   F    2   9    1   C    D   0 |
                    +--------+--------+--------+--------+





      H.2  Constructor Data Elements


           This section contains an example of each of the  constructor
      data  elements.    Each  example contains a short explanation and
      then an annotated series of  the  data  elements  making  up  the
      constructor.

           Property-List  data  element  containing  one  Property data
      element.    The  property  is  Printing-Name  and  its  value  is
      "Distribution":


           Prop-List  Length  Property  Length    PID
           +--------+--------+--------+--------+--------+
           |00100100|  1   1 |01000101|  0   F |  0   2 |
           +--------+--------+--------+--------+--------+

                      ASCII    Length
                    +--------+--------+----    ----+
                    |00000010|  0   C |Distribution|
                    +--------+--------+----    ----+

Top       Page 90 
           Printing-Name  Property.   The value of the Printing-Name is
      "Distribution":


            Property  Length    PID     ASCII    Length
           +--------+--------+--------+--------+--------+
           |01000101|  0   F |  0   2 |00000010|  0   C |
           +--------+--------+--------+--------+--------+

                    +----    ----+
                    |Distribution|
                    +----    ----+





           Compressed data element.  Its contents were compressed using
      an unspecified data compression algorithm.  The  compressed  data
      is in a bit-string that is 56 bits long, fully filling 7 octets:


           Compressed  Length   CID   Bit-String  Length
           +--------+--------+--------+--------+--------+
           |01000110|  0   B |  0   0 |01000011|  0   8 |
           +--------+--------+--------+--------+--------+

                       Spare
                    +--------+--------+--------+--------+
                    |  0   0 |  1   C    5   F    2   D
                    +--------+--------+--------+--------+

                    +--------+--------+--------+--------+
                       7   7    B   A    F   6    2   9 |
                    +--------+--------+--------+--------+

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           Encrypted  data  element.    The  encryption  method used to
      encrypt its contents has been intentionally not specified.   This
      element contains a Bit-String which contains 22 bits (((4-1) x 8)
      - 2) of data.  These 22 bits are represented in octets; the final
      2 bits in the final octet are padding and are therefore ignored:


           Encrypted   Length   EID   Bit-String  Length
           +--------+--------+--------+--------+--------+
           |01000111|  0   7 |  0   0 |01000011|  0   4 |
           +--------+--------+--------+--------+--------+

                       Spare
                    +--------+--------+--------+--------+
                    |  0   2 |  A   3    7   8    1   C |
                    +--------+--------+--------+--------+





           Date  data  element.    This  example includes a date but no
      time.  The date shown in this example is August 15, 1980:


             Date     Length   ASCII    Length
           +--------+--------+--------+--------+---  ---+
           |00101000|  0   A |00000010|  0   8 |19800815|
           +--------+--------+--------+--------+---  ---+





           Unique-ID data element, which is represented as  an  Integer
      data element whose value is 129 (decimal).


           Unique-ID  Length   Integer  Length
           +--------+--------+--------+--------+--------+--------+
           |00001001|  0   4 |00100000|  0   2 |  0   0    8   1 |
           +--------+--------+--------+--------+--------+--------+

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           Sequence  data element containing two ASCII-String data ele-
      ments.  The first ASCII-String is  "This  is"  while  the  second
      string is " a list":


            Sequence  Length   ASCII    Length
           +--------+--------+--------+--------+--- ---+
           |00001010|  1   2 |00000010|  0   7 |This is|
           +--------+--------+--------+--------+--- ---+

                      ASCII    Length
                    +--------+--------+--- ---+
                    |00000010|  0   7 | a list|
                    +--------+--------+--- ---+





           Set  data element containing two Integer data elements.  The
      first integer has a value of 519 (decimal) while the value of the
      second is 71 (decimal).   (These  two  values  have  no  ordering
      because they belong to a set.)


              Set     Length   Integer  Length
           +--------+--------+--------+--------+--------+--------+
           |00001011|  0   8 |00100000|  0   2 |  0   2    0   7 |
           +--------+--------+--------+--------+--------+--------+

                      Integer  Length
                    +--------+--------+--------+--------+
                    |00100000|  0   2 |  0   0    4   7 |
                    +--------+--------+--------+--------+





           Field  data  element.   The specific field shown is the Text
      field with the contents "I will see you at lunch.":


             Field    Length    FID      ASCII   Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   B |  0   4 |00000010|  1   8 |
           +--------+--------+--------+--------+--------+

                    +----                ----+
                    |I will see you at lunch.|
                    +----                ----+

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           Message containing four fields, Posted-Date, From, Text, and
      To.  It was sent on July 4, 1980 at 6 p.m. eastern daylight time.
      It  is  from  a person named Smith.  The text of the message is a
      question asking  the  recipient  "Are  you  going  to  watch  the
      fireworks?".  The message is sent to Jones:


            Message   Length    Type    Field    Length
           +--------+--------+--------+--------+--------+
           |01001101|  5   A |  0   1 |01001100|  1   9 |
           +--------+--------+--------+--------+--------+

                       FID      Date    Length   ASCII
                    +--------+--------+--------+--------+
                    |  0   2 |00101000|  1   6 |00000010|
                    +--------+--------+--------+--------+

                      Length
                    +--------+----            ----+
                    |  1   4 |19800704-180000-0400|
                    +--------+----            ----+


                      Field    Length    FID     ASCII
                    +--------+--------+--------+--------+
                    |01001100|  0   8 |  0   1 |00000010|
                    +--------+--------+--------+--------+

                      Length
                    +--------+-- --+
                    |  0   5 |Smith|
                    +--------+-- --+

                       Field   Length    FID     ASCII
                    +--------+--------+--------+--------+
                    |01001100|  2   8 |  0   4 |00000010|
                    +--------+--------+--------+--------+

                      Length
                    +--------+
                    |  2   5 |
                    +--------+

                    +----                             ----+
                    |Are you going to watch the fireworks?|
                    +----                             ----+

                      Field    Length    FID     ASCII
                    +--------+--------+--------+--------+
                    |01001100|  0   8 |  0   5 |00000010|
                    +--------+--------+--------+--------+

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                      Length
                    +--------+-- --+
                    |  0   5 |Jones|
                    +--------+-- --+





      H.3  Data Elements that Extend this Specification


           This  section  contains  examples  of  data elements used to
      extend this specification.  These data  elements  can  be  either
      primitives or constructors, depending on the extension.
           Extension  data  element  containing  a  length  code  and 3
      octets.  The octet immediately following the  length  code  iden-
      tifies it as Extension Data Element 7.  The Data Element Contents
      is  the final two octets.  The interpretation of the Data Element
      Contents would be defined in an extension or  successor  to  this
      message  format  specification.    [Note: this is an example. Any
      actual extension data element 7 (if it were ever used)  would  be
      completely different from anything done here.]:


           Extension  Length
           +--------+--------+--------+--------+--------+
           |01111110|  0   3 |  0   7 |  4   A    E   9 |
           +--------+--------+--------+--------+--------+





           Vendor-Defined  data  element containing a length code and 3
      octets.  The first octet identifies this as  vendor-defined  data
      element  number  114  (decimal), which this particular vendor has
      defined to  contain  three  printable  ASCII  characters  in  two
      octets.    (Data  element 114 (decimal) for another user would be
      completely different.  For example, it might contain  a  floating
      point number.):


              User    Length
           +--------+--------+--------+--------+--------+
           |01111111|  0   3 |  7   2 |   P    O    E   |
           +--------+--------+--------+--------+--------+

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      H.4  Fields


           This  section  contains  examples of Field data element con-
      structors for each of several different fields  (Keywords,  Text,
      Subject, Vendor-Defined).
           Field  data  element  for keywords .  The field contains two
      keywords, Message and Computer, each represented  in  a  separate
      ASCII-string data element.


              Field   Length  Keywords   ASCII   Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   4 |  1   4 |00000010|  0   7 |
           +--------+--------+--------+--------+--------+

                    +--- ---+
                    |Message|
                    +--- ---+

                      ASCII    Length
                    +--------+--------+---  ---+
                    |00000010|  0   8 |Computer|
                    +--------+--------+---  ---+

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           Field  data  element  for  Text  with  a  Property-List data
      element containing a comment attached.  The text  field  contains
      the ASCII-String data element "Do you want lunch?"; the Property-
      List  data element contains a comment property, which consists of
      an ASCII-string data element containing "Now?":


             Field    Length   Text    Prop-List  Length
           +--------+--------+--------+--------+--------+
           |11001100|  2   0 |  0   4 |00100100|  0   9 |
           +--------+--------+--------+--------+--------+

                     Property  Length    PID     ASCII
                    +--------+--------+--------+--------+
                    |01000101|  0   7 |  0   1 |00000010|
                    +--------+--------+--------+--------+

                      Length
                    +--------+-  -+
                    |  0   4 |Now?|
                    +--------+-  -+

                      ASCII    Length
                    +--------+--------+----          ----+
                    |00000010|  1   2 |Do you want lunch?|
                    +--------+--------+----          ----+





           Field data element for Subject  containing  an  ASCII-String
      data  element  ("Good  restaurants  in  Detroit"  followed  by  a
      carriage return and a line feed).  (A recipient would expect  the
      message  to  contain  some  information  about restaurants in the
      Detroit area.):


             Field    Length   Subject   ASCII   Length
           +--------+--------+--------+--------+--------+
           |01001100|  2   1 |  0   7 |00000010|  1   E |
           +--------+--------+--------+--------+--------+

                    +----                            ----+
                    |Good restaurants in Detroit.<cr><lf>|
                    +----                            ----+

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           Field  data  element whose form and meaning was defined by a
      vendor.    This  vendor  has  defined  vendor-defined  field   12
      (decimal)  to  be  a field with a printing name of "Reply-by" and
      contents consisting of a date; January  7,  1981  in  this  case.
      (The  meaning of vendor-defined field 12 is unique to the vendor;
      the same field number would  have  different  meaning  for  other
      vendors.):


             Field    Length  Qualifier   User   number
           +--------+--------+--------+--------+--------+
           |11001100|  1   F |  8   2 |  0   0    0   C |
           +--------+--------+--------+--------+--------+

                     Prop-List Length  Property  Length
                    +--------+--------+--------+--------+
                    |00100100|  0   E |01000101|  0   C |
                    +--------+--------+--------+--------+

                        PID    ASCII    Length
                    +--------+--------+--------+---- ----+
                    |  0   2 |00000010|  0   9 |Reply-By:|
                    +--------+--------+--------+---- ----+

                       Date    Length   ASCII    Length
                    +--------+--------+--------+--------+
                    |00101000|  0   A |00000010|  0   8 |
                    +--------+--------+--------+--------+

               +---  ---+
                    |19810107|
                    +---  ---+



      H.5  Messages


           This  section contains several examples of complete messages
      and shows the results of  reissuing  a  message.    (See  Section
      3.2.2.)

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           The  following  sample message had Stevens as its originator
      and Johnson as its recipient.  The message was sent on August 14,
      1980 at 10 a.m. EDT.  The subject  of  the  message  is  "Project
      Deadline"  and the message is a reminder that the deadline is the
      next day and that the section of the report for the project being
      done by Johnson should be turned in to Stevens  by  3  p.m.  that
      day.


            Message       Length         Type
           +--------+--------+--------+--------+
           |01001101|  8   1 |  B   6 |  0   1 |
           +--------+--------+--------+--------+

              Field   Length    FID     ASCII
           +--------+--------+--------+--------+
           |01001100|  0   A |  0   5 |00000010|
           +--------+--------+--------+--------+

                      Length
                    +--------+--- ---+
                    |  0   7 |Johnson|
                    +--------+--- ---+

             Field    Length    FID      ASCII
           +--------+--------+--------+--------+
           |01001100|  0   A |  0   1 |00000010|
           +--------+--------+--------+--------+

                      Length
                    +--------+--- ---+
                    |  0   7 |Stevens|
                    +--------+--- ---+

             Field    Length    FID     ASCII    Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   3 |  0   7 |00000010|  1   0 |
           +--------+--------+--------+--------+--------+

                    +----        ----+
                    |Project Deadline|
                    +----        ----+

             Field    Length    FID      Date    Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   7 |  0   2 |00101000|  1   4 |
           +--------+--------+--------+--------+--------+

Top       Page 99 
                      ASCII    Length
                    +--------+--------+----          ----+
                    |00000010|  1   2 |19800814-1000-0400|
                    +--------+--------+----          ----+

             Field    Length    FID      ASCII   Length
           +--------+--------+--------+--------+--------+
           |01001100|  6   D |  0   4 |00000010|  6   A |
           +--------+--------+--------+--------+--------+

                    +----
                    |Don't forget the project report is
                    +----

                     due tomorrow.  Please have<CrLf>

                     your section to me by three this

                           ----+
                     afternoon.|
                           ----+





           The  following  example illustrates the results of reissuing
      the first message in this section.   This  message  contains  the
      original  message  (as  a  Message  data  element), To, From, and
      Posted-Date fields, and a Reissue-Type field  with  Redistributed
      as its value:


            Message       Length         Type
           +--------+--------+--------+--------+
           |01001101|  8   1 |  F   C |  0   1 |
           +--------+--------+--------+--------+

              Field   Length    FID      ASCII
           +--------+--------+--------+--------+
           |01001100|  0   9 |  0   5 |00000010|
           +--------+--------+--------+--------+

                      Length
                    +--------+--  --+
                    |  0   6 |Cooper|
                    +--------+--  --+


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