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RFC 0806

 
 
 

Proposed Federal Information Processing Standard: Specification for message format for computer based message systems

Part 3 of 3, p. 70 to 107
Prev RFC Part

 


prevText      Top       Page 70 
      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.)


                 +--------+---//---+---//---+---//---+
                 |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|
                 +--------+---//---+---//---+

Top       Page 71 
      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
                constructor

                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 ems.     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 72 
                                 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 73 
                                 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 CBM 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

Top       Page 74 
      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 75 
                                 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.  (Appen  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 76 
      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 77 
                                 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 78 
           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 79 
                                 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                (constructor)  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 80 
      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           (constructor)  7F        377 
                                                16         8

Top       Page 81 
                                 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
      representation.   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|
           +--------+--------+

Top       Page 82 
           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.|
           +--------+--------+---- ----+

Top       Page 83 
           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 84 
           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 as-yet-undefined NBS standard 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   1 |01000011|  0   8 |
           +--------+--------+--------+--------+--------+

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

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

Top       Page 85 
           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 |
           +--------+--------+--------+--------+--------+--------+

Top       Page 86 
           Sequence  data  element  containing  two  ASCII-String  data
      elements.  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  value  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.|
                    +----                ----+

Top       Page 87 
           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   8 |  0   1 |01001100|  1   7 |
           +--------+--------+--------+--------+--------+

                       FID      Date    Length   ASCII
                    +--------+--------+--------+--------+
                    |  0   2 |00101000|  1   4 |00000010|
                    +--------+--------+--------+--------+

                      Length
                    +--------+----          ----+
                    |  1   2 |19800704-180000EDT|
                    +--------+----          ----+


                      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|
                    +--------+--------+--------+--------+

Top       Page 88 
                      Length
                    +--------+-- --+
                    |  0   5 |Jones|
                    +--------+-- --+





           Extension  data  element  containing  a  length  code  and 3
      octets.    The  octet  immediately  following  the  length   code
      identifies  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   |
           +--------+--------+--------+--------+--------+



      H.3  Fields


           This  section  contains  examples  of  Field  data   element
      constructors  for  each several different fields (Keywords, Text,
      Subject, Vendor-Defined).

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           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|
                    +--------+--------+---  ---+





           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?|
                    +--------+--------+----          ----+

Top       Page 90 
           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.4  Messages


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

Top       Page 92 
           The  following  sample message had Stevens as its originator
      and Johnson as its recipient.  The message was sent on August 14,
      1980 at 10 am 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 pm that day.


            Message       Length         Type
           +--------+--------+--------+--------+
           |01001101|  8   1 |  B   4 |  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   5 |  0   2 |00101000|  1   2 |
           +--------+--------+--------+--------+--------+

                      ASCII    Length
                    +--------+--------+----        ----+
                    |00000010|  1   0 |19800814-1000EDT|
                    +--------+--------+----        ----+

Top       Page 93 
             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   8 |  0   1 |
           +--------+--------+--------+--------+

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

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

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

Top       Page 94 
                      Length
                    +--------+--- ---+
                    |  0   7 |Johnson|
                    +--------+--- ---+

             Field    Length    FID      Date    Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   5 |  0   2 |00101000|  1   2 |
           +--------+--------+--------+--------+--------+

                       ASCII   Length
                    +--------+--------+----        ----+
                    |00000010|  1   0 |19800814-1030EDT|
                    +--------+--------+----        ----+

             Field    Length    FID      ASCII   Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   0 |  2   5 |00000010|  0   D |
           +--------+--------+--------+--------+--------+

                    +----     ----+
                    |Redistributed|
                    +----     ----+

            Message       Length         Type
           +--------+--------+--------+--------+
           |01001101|  8   1 |  B   4 |  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|
                    +--------+--- ---+

Top       Page 95 
             Field    Length    FID     ASCII    Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   3 |  0   7 |00000010|  1   0 |
           +--------+--------+--------+--------+--------+

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

             Field    Length    FID      Date    Length
           +--------+--------+--------+--------+--------+
           |01001100|  1   5 |  0   2 |00101000|  1   2 |
           +--------+--------+--------+--------+--------+

                      ASCII    Length
                    +--------+--------+----        ----+
                    |00000010|  1   0 |19800814-1000EDT|
                    +--------+--------+----        ----+

             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.|
                           ----+



      H.5  Unknown Lengths


           This  section contains two examples of data elements with an
      unknown length.  The two examples have been presented in sections
      H.2 and H.4, but with a known rather than an unknown length.

Top       Page 96 
           Set  data  element  with  an  unknown  length 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 value have no ordering because they belong to a set.)


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

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

                    End-of-Con Length
                    +--------+--------+
                    |00000000|00000000|
                    +--------+--------+






           The following sample message  with  an  unknown  length  had
      Stevens  as  its  originator  and  Johnson as its recipient.  The
      message was sent on August 14, 1980 at 10 am 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 pm that day.


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

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

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

Top       Page 97 
             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   5 |  0   2 |00101000|  1   2 |
           +--------+--------+--------+--------+--------+

                      ASCII    Length
                    +--------+--------+----        ----+
                    |00000010|  1   0 |19800814-1000EDT|
                    +--------+--------+----        ----+

             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.|
                           ----+

                    End-of-Con Length
                    +--------+--------+
                    |00000000|00000000|
                    +--------+--------+

Top       Page 98 
                                 REFERENCES




      [BlaR-80]
           R. P. Blanc and J. F. Heafner. The NBS Program in Computer
           Network Protocol Standards. In Proceedings, ICCC 80.  1980.

      [CroD-77]
           David H. Crocker, John J. Vittal, Kenneth T. Pogran,
           D. Austin Henderson, Jr. Standard for the Format of ARPA
           Network Text Messages. RFC 733, The Rand Corporation, Bolt
           Beranek and Newman Inc, Massachussets Institute of
           Technology, Bolt Beranek and Newman Inc., November, 1977.

      [FeiE-79]
           E. Feinler, J. Pickens, and A. Sjoberg. Computer Message
           Services Bibliography. Technical Report NIC-BIBLIO-791201,
           SRI International, December, 1979.

      [ISOD-79]
           ISO/TC97/SC6 Data Communications. Second Draft Proposed
           Communication Heading Format Standard. ISO/TC97/SC6 N 1948,
           ISO International Organization for Standardization
           Organization Internationale de Normalisation, September,
           1979. Secretariat: USA (ANSI).

      [ISOD-81]
           ISO/TC97/SC16. Open Systems Interconnection Basic Reference
           Model. ISO/TC97/SC16 N, ISO International Ozation for
           Standardization Organization Internationale de
           Normalisation, 1981.

      [NatB-68]
           National Bureau of Standards. Calendar Date. Federal
           Information Processing Standards Publication 4, U.S.
           Department of Commerce / National Bureau of Standards,
           November, 1968.

      [NatB-77]
           National Bureau of Standards. Data Encryption Standard.
           Federal Information Processing Standards Publication 46,
           U.S. Department of Commerce / National Bureau of Standards,
           January, 1977.

      [NatB-79a]
           National Bureau of Standards. Representations of Local Time
           of the Day for Information Interchange. Federal Information
           Processing Standards Publication 58, U.S. Department of
           Commerce / National Bureau of Standards, February, 1979.

Top       Page 99 
      [NatB-79b]
           National Bureau of Standards. Representations of Universal
           Time, Local Time Differentials, and United States Time Zone
           References for Information Interchange. Federal Information
           Processing Standards Publication 59, U.S. Department of
           Commerce / National Bureau of Standards, February, 1979.

      [PosJ-79]
           Jonathan B. Postel. INTERNET MESSAGE PROTOCOL. RFC 753,
           Information Sciences Institute, March, 1979.

      [SchP-79]
           Peter Schicker. The Computer Based Mail Environment: An
           Overview. Technical Report, Bell-Northern Research Ltd.,
           Ottawa, Ontario, Canada, December, 1979.

      [TasG-80]
           Task Group X3S33 on Data Communications Formats, ANSI
           Subcommittee X3S3 on Data Communications. Third Draft
           Proposed American National Standard for Heading Format
           Structure for Code Independent Communication Headings. ANSI
           document X3S37/80-01, Computer and Business Equipment
           Manufacturers Association, 1980.

Top       Page 100 
                                    INDEX





                ASCII-String   29, 30, 42, 45, 47, 49, 53, 54, 55, 57,
                        59, 63
                Assignment   17, 22, 55
                Attachments   17, 52
                Audit trail   20
                Author   14, 52

                BASIC   13
                BASIC Data Elements
                   ASCII-String   42, 57
                   Date   45, 59
                   End-of-Constructor   43, 60
                   Field   46, 60
                   Message   46, 61
                BASIC fields
                   Cc   14
                   Reply-To   14
                   Subject   17
                   Text   17
                BASIC syntactic elements   29
                Bcc   14, 19, 20, 52
                Bit numbering in octets   32
                Bit-String   30, 37, 42, 44, 45, 47, 57, 58, 59, 63
                Boolean   30, 43, 58

                Cc   14, 19, 52
                Chains of correspondence   24
                Circulate-Next   15, 26, 53
                Circulate-To   15, 26, 53
                Circulation   26
                Comment   30, 31, 38, 49
                Comments   18, 53
                Compliance requirements   34
                Compressed   31, 37, 44, 49, 58
                Compression identifier   44, 58
                Compression Identifiers
                   NBS-Standard   49
                   Unspecified   49
                Constructor data element   29, 30
                Contents   32, 70
                Cross Referencing   24

                Data Element Contents   37, 38, 39, 81, 36, 39, 47, 63,
                        36, 38, 39, 41, 42, 47, 57, 63, 81
                Data Elements

Top       Page 101 
                   ASCII-String (BASIC)   42, 57
                   Bit-String (OPTIONAL)   42, 57
                   Boolean (OPTIONAL)   43, 58
                   Compressed (OPTIONAL)   44, 58
                   Date (BASIC)   45, 59
                   Encrypted (OPTIONAL)   45, 59
                   End-of-Constructor (BASIC)   43, 60
                   Extension (OPTIONAL)   45, 60
                   Field (BASIC)   46, 60
                   Integer (OPTIONAL)   43, 61
                   Message (BASIC)   46, 61
                   No-Op (OPTIONAL)   44, 61
                   Padding (OPTIONAL)   44, 62
                   Property (OPTIONAL)   47, 62
                   Property-List (OPTIONAL)   46, 62
                   Sequence (OPTIONAL)   47, 63
                   Set (OPTIONAL)   47, 63
                   Unique-ID (OPTIONAL)   47, 63
                   Vendor-Defined (OPTIONAL)   48, 64
                Date   15, 45, 53, 54, 55, 56, 59
                Dating   25
                Delivery   9, 15, 54
                Delivery Protocol   9
                Delivery Slot   9

                Encapsulating   22
                Encrypted   31, 37, 45, 49, 59
                Encryption identifier   45, 59
                Encryption Identifiers
                   NBS-Standard   49
                   Unspecified   49
                End-Date   15, 25, 53, 56
                End-Of-Constructor   30, 36, 39, 43, 60
                Extension   41, 45, 60

                Field   10, 26, 29, 30, 31, 37, 46, 60, 61, 66
                Field Identifier   46, 60
                Field label presentation   29
                Fields
                   Attachments (OPTIONAL)   52, 17
                   Author (OPTIONAL)   52, 14
                   Bcc (OPTIONAL)   52, 14
                   Cc (BASIC)   52, 14
                   Circulate-Next (OPTIONAL)   53, 15
                   Circulate-To (OPTIONAL)   53, 15
                   Comments (OPTIONAL)   53, 18
                   Date (OPTIONAL)   53, 15
                   End-Date (OPTIONAL)   53, 15
                   From (REQUIRED)   53, 14
                   In-Reply-To (OPTIONAL)   53, 16
                   Keywords (OPTIONAL)   53, 18

Top       Page 102 
                   Message-Class (OPTIONAL)   54, 17
                   Message-ID (OPTIONAL)   54, 16
                   Obsoletes (OPTIONAL)   54, 16
                   Originator-Serial-Number (OPTIONAL)   54, 16
                   Posted-Date (REQUIRED)   54, 15
                   Precedence (OPTIONAL)   54, 16
                   Received-Date (OPTIONAL)   54, 15
                   Received-From (OPTIONAL)   55, 17
                   References (OPTIONAL)   55, 16
                   Reissue-Type (OPTIONAL)   55, 17
                   Reply-To (BASIC)   55, 14
                   Sender (OPTIONAL)   55, 14
                   Start-Date (OPTIONAL)   55, 15
                   Subject (BASIC)   55, 17
                   Text (BASIC)   56, 17
                   To (REQUIRED)   56, 14
                   Warning-Date (OPTIONAL)   56, 15
                From   12, 14, 23, 52, 53, 55

                Globally unique identifiers   24

                Identifier octet   33, 35, 32, 33, 36, 39, 40, 70
                Identifiers
                   globally unique   24
                In-Reply-To   16, 24, 53
                Indefinite length code   35
                Integer   30, 43, 47, 61, 63

                Keywords   18, 53, 81

                Length Code   34, 36, 32, 33, 34, 35, 36, 37, 39, 40,
                        70, 71, 81
                Long length code   35

                Message Transfer System   8, 9, 17, 54
                Message   10, 12, 29, 30, 31, 37, 46, 61
                Message content   9
                Message envelope   9
                Message stores   25
                Message Transfer System   9, 17, 20, 55, 8, 9, 10, 12,
                        15, 16, 20, 54, 55
                Message Types
                   NBS-Standard   50
                Message-Class   17, 54
                Message-ID   16, 24, 26, 53, 54, 55

                NBS-Standard   49, 50
                No-Op   44, 61
                Numbering bits in octets   32

                Obsoletes   16, 24, 54

Top       Page 103 
                Octets
                   bit numbering in   32
                OPTIONAL   13
                OPTIONAL Data Elements
                   Bit-String   42, 57
                   Boolean   43, 58
                   Compressed   44, 58
                   Encrypted   45, 59
                   Extension   45, 60
                   Integer   43, 61
                   No-Op   44, 61
                   Padding   44, 62
                   Property   47, 62
                   Property-List   46, 62
                   Sequence   47, 63
                   Set   47, 63
                   Unique-ID   47, 63
                   Vendor-Defined   48, 64
                OPTIONAL fields
                   Attachments   17
                   Author   14
                   Bcc   14
                   Circulate-Next   15
                   Circulate-To   15
                   Comments   18
                   Date   15
                   End-Date   15
                   In-Reply-To   16
                   Keywords   18
                   Message-Class   17
                   Message-ID   16
                   Obsoletes   16
                   Originator-Serial-Number   16
                   Precedence   16
                   Received-Date   15
                   Received-From   17
                   References   16
                   Reissue-Type   17
                   Sender   14
                   Start-Date   15
                   Warning-Date   15
                OPTIONAL syntactic elements   29
                Originator   11, 13, 15, 25, 52, 53, 55
                Originator-Serial-Number   16, 25, 54

                Padding   44, 62
                Person   13
                Posted-Date   12, 15, 26, 53, 54
                Posting   9
                Posting Protocol   9
                Posting Slot   9

Top       Page 104 
                Precedence   16, 54
                Precedence categories   17
                Precedence scheme   54
                Presentation
                   field label   29
                Primitive data element   30, 29, 30
                Printing-Name   30, 38, 49, 76
                Process   13
                Properties
                   Comment   49
                   Printing-Name   49
                Property   32, 37, 46, 47, 62
                Property-Identifier   47, 62
                Property-List   30, 32, 33, 38, 39, 40, 46, 62, 70

                Qualifier   32, 33, 34, 36, 37, 39, 40, 42, 44, 45, 46,
                        47, 48, 57, 58, 59, 60, 62, 64, 70
                Qualifiers   37

                Received-Date   15, 54
                Received-From   17, 55
                Recipient   11, 14, 17, 52, 53, 55, 56
                Redistribution   17, 22, 55
                References   16, 24, 55
                Reissue-Type   17, 55
                Reply   13, 23
                Reply-to   14, 23, 53, 55
                REQUIRED   13
                REQUIRED fields
                   From   14
                   Posted-Date   15
                   To   14
                Requirements
                   compliance   34
                Role   13

                Sender   14, 26, 55
                Sequence   29, 30, 47, 63
                Sequences   30
                Serial Numbers   16, 24, 54
                Set   30, 47, 63
                Short length code   35
                Slot   9
                Start-Date   15, 25, 55
                Subject   17, 55
                Syntactic reissuing   22

                Text   17, 26, 56
                To   12, 14, 19, 26, 30, 56

                Unique identifiers   24

Top       Page 105 
                Unique-ID   47, 53, 54, 55, 63
                Unspecified   49
                User Agent   8, 9, 20
                User interface   29

                Vendor-Defined   41, 48, 64

                Warning-Date   15, 25, 56