rfc767.txt

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  The document is a property list of <name,value> pairs called fields.
  A few fields are specifically required and many are optional.  Some of
  the field values are simple and a few are quite complicated.  In
  particular the body value may be highly structured.

  Older message systems have considered the document to be divided into
  a header and a body, and have used keywords to indicate specific
  header fields (e.g., date, to, subject).  Roughly speaking, this
  functionality is provided in this new structured format by considering
  the name part of the <name,value> pair to be a keyword.  In addition,
  this new structured format eliminates the separate treatment of the
  body.

  It is impossible to foresee the many forms documents will take so the
  standard for a document header must be flexible.  The approach here is
  to define a set of basic fields and allow addition of whatever fields
  are necessary.  Features added in this fashion may not be understood
  by others.

  The minimum document is a property list of the following fields:

    Name     Value
    ----     -----
    DATE     date string (name)
    SENDER   a mailbox
    SUBJECT  subject string (text)
    BODY     a data structure

  A typical document is a property list containing the following fields:

    Name     Value
    ----     -----
    DATE     date string (name)
    SENDER   a mailbox
    FROM     list of mailboxes
    TO       list of mailboxes
    CC       list of mailboxes
    SUBJECT  subject string (text)
    BODY     a data structure





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  An elaborate document might contain the following fields:

    Name        Value
    ----        -----
    DATE        date string (name)
    SENDER      a mailbox
    FROM        list of mailboxes
    TO          list of mailboxes
    CC          list of mailboxes
    BCC         list of mailboxes
    REPLY-TO    list of mailboxes
    SUBJECT     subject string (text)
    COMMENTS    comment string (text)
    MESSAGE-ID  message identifier of this message (text)
    IN-REPLY-TO message identifier of previous message (text)
    REFERENCES  message identifiers of other messages (text)
    KEYWORDS    key terms used in this message (text)
    BODY        a data structure

  One of the key objects is the mailbox.  It appears in the sender,
  from, to, cc, bcc, and reply-to fields.  The mailbox is a property
  list of objects that combine to specify a destination recipient for a
  message.  Most of the <name,value> pairs that make up a mailbox are
  identical to those used in the deliver command in the Internet Message
  Protocol [1].  A few additional <name,value> pairs are defined for use
  in a mailbox in the document context.  In particular, there is a field
  for the real name of a person in contrast to the "user name" which
  identifies a computer account.

  In addition there is a field to specify a distribution group name.
  Such group names are used to indicate that a document is being sent to
  a group of recipients.  This essentially presents an alternate form
  for a mailbox which consists of the single <name,value> pair for the
  group name.  There is no required relationship between a group name
  mailbox and other mailboxes in the same list.

  For example, all of the following situations are allowed:

    .  a mailbox list consisting of a single mailbox specifying a
       particular user,

    .  a mailbox list consisting of a single mailbox with a group name,

    .  a mailbox list consisting of a mailbox with a group name and a
       mailbox specifying a particular user, with either the user in or
       not in the group,

    .  a mailbox list consisting of a mailbox with a group name and a


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       several mailboxes specifying a particular users, with some users
       in the group and some not,

    .  a mailbox list consisting of several mailboxes specifying group
       names and a several mailboxes specifying a particular users, with
       some users in the groups and some not.

    

2.2.  Message Objects

  In the documents of messages, we use a set of objects such as mailbox
  or date.  These objects are encoded in basic data elements.  Some
  objects are simple things like integers or character strings, other
  objects are more complex things like lists or property lists.  The
  following is a list of the objects used in messages.  The object
  descriptions are in alphabetical order.

  Account

    The account information.  Represented by a name element.

  Address

    Address is intended to contain the minimum information necessary to
    identify a user, and no more (compare with mailbox).

    An address is a property list which contains the following
    <name,value> pairs:

      name    description
      ----    -----------
      NET     network name
      HOST    host name
      USER    user name

    or:

      name    description
      ----    -----------
      MPM     mpm-identifier
      USER    user name

  Answer

    A yes (true) or no (false) answer to a question.  Represented by a
    boolean element.



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  BCC

    A list of mailboxes.  The addresses of those who receive "blind
    carbon copies" of the message.

  Body

    A data structure.  This may be as simple as a character string
    (represented by a name or text element), or complex structure of
    lists.  It may be encrypted in part or in whole.  Section 3.3
    describes some possible structured bodies.

  C

    A character.  Represented by a name element.

  CC

    A list of mailboxes.  When copies of a message are sent to others in
    addition to the addresses in the To object, those to whom the copies
    are sent will have their addresses recorded here.

  City

    A city.  Represented by a name element.

  Comments

    A comment string.  Represented by a text element.

  Count

    A count of items of some sort.  Represented by a integer element.

  Country

    A country.  Represented by a name element.













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  Date

    The date and time are represented according to the International
    Standards Organization (ISO) recommendations [19,20,21].  Taken
    together the ISO recommendations 2014, 3307, and 4031 result in the
    following representation of the date and time:

      yyyy-mm-dd-hh:mm:ss,fff+hh:mm

    Where yyyy is the four-digit year, mm is the two-digit month, dd is
    the two-digit day, hh is the two-digit hour in 24 hour time, mm is
    the two-digit minute, ss is the two-digit second, and fff is the
    decimal fraction of the second.  To this basic date and time is
    appended the offset from Greenwich as plus or minus hh hours and mm
    minutes.

    The time is local time and the offset is the difference between
    local time and Coordinated Universal Time (UTC).  To convert from
    local time to UTC algebraically subtract the offset from the local
    time.

    For example, when the time in
              Los Angeles is  14:25:00-08:00
              the UTC is      22:25:00

    or when the time in
              Paris is        11:43:00+01:00
              the UTC is      10:43:00

  Device

    A device name.  Represented by a name element.

  Document

    A property list of fields.

  Distribution Group

    An distribution group is a property list which contains the
    following <name,value> pair:

      name    description
      ----    -----------
      GROUP   document distribution group name

    This construct is used so that a distribution group will be a
    special case of a mailbox.


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  Facsimile Structure

    A facsimile data structure.  Represented by a property list.

  File

    A file name.  Represented by a name element.

  Format

    A format indicator.  Represented by a name element.

  From

    A list of mailboxes.  The From is the name of the author of a
    document.

  Graphics Structure

    A graphics data structure.  Represented by a property list.

  Group

    A document distribution group name.  Represented by a name element.

  Host

    A host name.  Represented by a name element.

  Ident

    The identifier of a person, usually their initials.  Represented by
    a name element.

  In-Reply-To

    The message identifier of previous message.  Represented by a text
    element.

  Internet Address

    This identifies a host in the ARPA internetwork environment.  The
    internet address is a 32 bit number, the higher order 8 bits
    identify the network, and the lower order 24 bits identify the host
    on that network [22].  For use in this format the internet address
    is divided into eight bit fields and the value of each field is
    represented in decimal digits.  For example, the ARPANET address of
    ISIE is 167837748 and is represented as 10,1,0,52.  Further, this


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    representation may be extended to include an address within a host,
    such as the TCP port of an MPM, for example, 10,1,0,52,0,45.

  Keywords

    The key terms used in this message.  Represented by a text element.

  Mailbox

    This is the destination address of a user of the internetwork mail
    system.  Mailbox contains information such as network, host,
    location, and local user identifier of the recipient of the message.
    The mailbox may contain information in addition to the minimum
    required for delivery.

    As an example, when one sends a message to someone for the first
    time, he may include many items to aid in identifying the correct
    recipient.  However, once he gets a reply to this message, the reply
    will contain an Address (as opposed to Mailbox) which may be used
    from then on.

      A mailbox is a property list.  A mailbox might contain the
      following <name,value> pairs:

        name    description
        ----    -----------
        MPM     mpm-identifier
        NET     network name
        HOST    host name
        PORT    address of MPM within the host
        USER    user name (computer account name)
        PERSON  the real name of a person
        GROUP   document distribution group
        ORG     organization name
        CITY    city
        STATE   state
        COUNTRY country
        ZIP     zip code
        PHONE   phone number

    The minimum mail box is an Address or a Distribution Group.

  Message-ID

    The message identifier of this message.  This is not related to the
    MPM message identification, but is a UIP long term document
    identifier.  Represented by a text element.



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  MPM-Identifier

    The internetwork address of an MPM.  This may be the ARPA Internet
    Address or an X.121 Public Data Network Address [23].  The
    mpm-identifier is a property list which has one <name,value> pair.
    This unusual structure is used so that it will be easy to determine
    the type of address used.

  Net

    A network name.  Represented by a name element.

  NLS Block

    The information in an NLS node.  Represented by a property list.

  NLS Node

    An NLS block and substructure.  Represented by a property list.

  NLS Substructure

    A list of NLS nodes.  Represented by a list.

  Org

    An organization name.  Represented by a name element.

  Paragraph

    A paragraph of text.  Represented by a text element.

  Parcel

    The basic unit of voice data.  Represented by a bitstr element.

  Person

    The real name of a person.  Represented by a name element.

  Password

    A password.  Represented by a name element.

  Phone

    A phone number.  Represented by a name element.



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  Pointer

    A pointer to information stored outside this data structure.  A
    property list containing the information necessary to locate the