                     Internet RFC/STD/FYI/BCP Archives



                                   RFC724

             [ Index | Search | What's New | Comments | Help ]
  ------------------------------------------------------------------------

     RFC #  724
     NIC #37435                                            12 May 1977

                    Proposed Official Standard for the
                      Format of ARPA Network Messages

                                    by

              Ken Pogran, MIT-LCS/CSR    (Pogran at MIT-Multics)
              John Vittal, BBN            (Vittal at BBN-TENEXA)
              Dave Crocker, RAND-ISD     (DCrocker at Rand-Unix)
              Austin Henderson, BBN    (Henderson at BBN-TENEXD)

     Proposed Standard for Message Format                         / ii

                                  PREFACE

          ARPA's  Committee  on  Computer-Aided  Human   Communication
     (CAHCOM) wishes to promulgate an official standard for the format
     of ARPA Network mail headers which will adequately meet the needs
     of  the  various message service subsystems on the Network today.
     The authors  of  this  RFC  constitute  the  CAHCOM  subcommittee
     charged  with  the  task  of  developing  this new standard; this
     document presents our  current  thoughts  on  the  matter  and  a
     specific proposal.

          This document is organized as follows: First, we  present  a
     history,  of the development of what has become known as the ARPA
     Network "mail" or "message" service, and the issues which we feel
     are  most  pressing  --  problems for which solutions are lacking
     today, inhibiting the further development of message  subsystems.
     We  then  present  the  specification  for  the  new ARPA Network
     Message Header  standard.   This  is  followed  by  a  References
     section.

          Essentially, we propose a revision to Request  for  Comments
     (RFC)  561,  "Standardizing  Network  Mail Headers", and RFC 680,
     "Message  Transmission  Protocol".   This  revision  removes  and
     compacts  portions  of  the  previous  syntax  and  adds  several
     features to network address  specification.   In  particular,  we
     focus  on  people  and  not  mailboxes  as  recipients  and allow
     reference to stored address lists.   We  expect  this  syntax  to
     provide  sufficient  capabilities  to  meet most users' immediate
     needs and, therefore, give developers enough  breathing  room  to
     produce  a new mail transmission protocol "properly".  We believe
     that there is enough of a consensus in the Network  community  in
     favor  of such a standard syntax to make possible its adoption at
     this time.

          We would like to make clear  the  status  of  this  proposed
     standard:  The CAHCOM Steering Committee has replaced the Message
     Service Committee as the ARPANET  standards-setting  organization
     in  the  area  of  message  services.   It  is  expected that the
     proposal of this CAHCOM subcommittee, when  in  its  final  form,
     will  be  adopted  as  an  ARPANET  standard  by  CAHCOM.  In the
     interests of making this standard the best possible one,  we  are
     distributing  this  proposal as an RFC.

          Please send any  comments  and  criticisms  to  any  of  the
     authors  of  this  RFC  by  15 June 1977.  It is planned that the
     standard will be officially adopted by  1  September  1977,  with
     hosts expected to accept its syntax by 1 January 1978.

     Proposed Standard for Message Format                        / iii

                             CONTENTS

                  I.  PROBLEMS WITH ARPANET
                      MESSAGE STANDARDS

                      A.  Background and History
                      B.  Issues and Conclusions
                      C.  Message Parts
                      D.  Adoption of the Standard

                 II.  STANDARD FOR THE FORMAT
                      OF ARPA NETWORK MESSAGES

                      A.  Framework
                      B.  Syntax
                      C.  Semantics
                      D.  Examples

                III.  REFERENCES

                              APPENDIX

                  A.  Alphabetical Listing of Syntax Rules

     I. Problems with ARPANET Message Standards                    / 1
     A. Background and History

              I.  PROBLEMS WITH ARPANET MESSAGE STANDARDS

     A.  BACKGROUND AND HISTORY

          Today's ARPA Network "mail" or "message" service  uses,  for
     its delivery mechanism, two special commands of the File Transfer
     Protocol.  Viewed from within the structure of  FTP,  the  entire
     message,  both header and text, is data for the FTP MAIL and MLFL
     commands.  This facility was added to the File Transfer  Protocol
     as  an  afterthought;  it was an interim solution to be used only
     until  a  separate  mail  transmission  protocol  was  specified.
     Several  versions of such a protocol have been proposed, but none
     has yet received general acceptance.   Meanwhile,  attempts  have
     been made to improve upon the original interim facility.

          As  message  service  subsystems  on  various  host  systems
     (especially  TENEX)  developed  to  the  point  where rudimentary
     parsing of incoming messages was being done, it became clear that
     it  would  be  desirable to standardize the format and content of
     the headers of messages transmitted between hosts using these FTP
     commands.   To this end, an ad hoc committee wrote RFC 561, which
     suggested a standard message header format.   The  committee  was
     unofficial,  so  it could not legislate a standard, it could only
     recommend.  However, the standard it suggested adequately met  an
     urgent need, and was generally adopted.

          Several  salient  points should be noted:

          1. RFC 561 defined the concept  of  a  message  header,  and
             specified  the  syntax which delimited it from the actual
             text of a message;

          2. It proposed a standard format for the  most  obvious  and
             most  urgently-needed header items: "From:", "Date:", and
             "Subject:";

          3. It proposed that a general standard syntax  be  used  for
             all other header items;

          4. RFC 561 is still, today, an unofficial standard,  adhered
             to by most because of its utility;

          5. Its syntax was designed to allow humans to read the  text
             easily,  without  the  aid  of special message processing
             systems.

     I. Problems with ARPANET Message Standards                    / 2
     A. Background and History

          As message services grew in  sophistication,  the  need  for
     specific header items in RFC 561's "miscellaneous" category grew:
     "To:" and "cc:", especially, were  generated  and  recognized  by
     several  different  message  services.   However,  there  was  no
     specific standard for the syntax of the contents of these  items.
     The  message  service  subsystems on TENEX developed a particular
     format for these items; since more messages originated  from  the
     TENEX  hosts  on  the  Network  than  from any other type of host
     system, the TENEX format for these fields soon became a de  facto
     standard.   Message  service  subsystems  on TENEX began to parse
     these fields, expecting them to be in the TENEX-generated format.
     Message service subsystems on other hosts -- Multics, for example
     -- began to dabble with other formats  for  these  fields,  since
     there  was  no standard for them, only to receive complaints from
     users of  TENEX  message  service  subsystems  that  their  "non-
     standard"  message  headers  could not be parsed according to the
     (de facto) "standard" syntax.

          Recognizing that the time had come to  make  an  attempt  to
     standardize  the  additional header fields that had come into use
     since RFC 561 was published,  ARPA's  Message  Service  Committee
     chartered  a  small group in 1975 to develop a revised version of
     RFC 561 which would define the syntax of these additional message
     header  fields.   Several things should be noted about this small
     group of  people:  first,  they  were  TENEX-oriented;  when  the
     functionality  of  the  message  header  items  they  desired was
     matched by  the  functionality  of  an  already-existing  message
     header  item  of  the  TENEX message subsystems, they adopted the
     syntax used by the TENEX message subsystems.  Second, they  based
     additional  header  items  not  already  found  on  TENEX message
     subsystems on the deliberations of the Message Service Committee.
     Third,  they were not familiar with the procedure for publication
     of a document as a Network RFC.

          The document which this group produced,  labelled  RFC  680,
     "Message    Transmission   Protocol",   received   only   limited
     distribution.  Matters were further confused  because  its  title
     was  misleading, since it was not a protocol for the transmission
     of messages between ARPA Network hosts, but rather a standard for
     the format of messages transmitted via the standard File Transfer
     Protocol.    Some,   including  the  Message  Service  Committee,
     believed that RFC 680 became a Network Standard.   This  was  not
     strictly true, because it never received proper distribution, and
     it had never been "officially blessed" by anyone, to turn it from
     a  request  for  comments  into an accepted official ARPA Network
     standard document.  Reflecting this confusion over the status  of
     the  document  are  the  facts  that  the document DOES currently
     reside in the "official"  ARPANET  Protocol  Handbook,  and  most
     users and message system implementors remain unaware that this is
     so.

     I. Problems with ARPANET Message Standards                    / 3
     A. Background and History

          For all its shortcomings, RFC 680  has  performed  a  needed
     service,  just  as  did RFC 561 before it.  It defined additional
     message header items at a time  when  this  needed  to  be  done.
     Unfortunately,  since  the  group  had not sought ideas and input
     from others, the specification did not adequately  respond  to  a
     sufficient  set  of  community needs.  In addition, the manner in
     which the document was promulgated -- or not promulgated --  left
     a great deal to be desired.  Implementators of message-processing
     subsystems who had not received RFC 680 proceeded to go their own
     ways, feeling justified in doing so, while those who accepted RFC
     680 as a standard felt justified in complaining to --  and  about
     --  those  whom  they  considered  to be maverick implementors of
     idiosyncratic message service subsystems.

          Perhaps because of the ad-hoc nature  of  the  interim  mail
     facility,  users  have not, until recently, attempted to push the
     system to the limits of their imagination.   Presently,  however,
     several different sites are using the "interim" mail facility for
     more than it was designed and in ways which are incompatible both
     with  each  other  and  with the original intent of the facility.
     Mail subsystem  implementors  are  increasingly  being  asked  to
     provide for the handling of mail from idiosyncratic hosts.  Also,
     it has become clear that there are a few very  specific features,
     too useful to ignore, which cannot reasonably be specified within
     the syntax of RFC 680.

     B.  ISSUES AND CONCLUSIONS

          At first glance, it would seem that a resolution of  today's
     somewhat  chaotic situation could best be obtained by immediately
     junking the existing "interim" mail facility, and adopting a true
     mail  transmission protocol.  We strongly believe that this would
     be ill-advised at this time, for we feel that there is no general
     understanding  within  the  Network  community  today  of  how to
     specify and implement  a  full  and  adequate  mail  transmission
     protocol.   However,  we  are convinced that there is, finally, a
     strong commitment within the Network  community  to  attack  this
     problem  (which  there  was  not  at  the time the "interim" mail
     transmission facility was specified and developed).

          The frontal attacks on the mail protocol  problem  have,  so
     far, resulted in at least two suggestions for a mail transmission
     protocol.  Why should not  one  of  these  protocols  be  adopted
     immediately? We feel that, in general, there has been a  tendency
     for  experimental  Network  software to be prematurely treated as
     though  it  were  adequately  designed  and  fully   operational.
     Typically, the system or protocol proposed is so much better than
     what was previously available that  its  experimental  nature  is
     disregarded,  and  it is pressed into service before it has had a

     I. Problems with ARPANET Message Standards                    / 4
     B. Issues and Conclusions

     chance to properly develop and mature.   We  are  very  concerned
     that this phenomenon not afflict the Network mail system any more
     than it already has.

          While it is true that there are several sites  in  the  ARPA
     Community  which  have  mail  systems  that understand the syntax
     specified in RFC's 561 and 680, in addition to some of the  "non-
     standard"  syntax  provided  by  the  mail generating programs at
     several other sites, most mail systems do not parse much  of  the
     contents  of  received  messages.   A consideration of the syntax
     specified here is that messages which are sent to  people  should
     be  easily  read  by  people.   Parsers  which  can turn an ugly,
     syntactically expedient form into something which is easy to read
     are  the  exception,  rather  than  the  rule, in today's message
     systems.  Also, the modifications to the existing  "non-standard"
     syntax  should  be  kept  to a minimum, enhancing the probability
     that the requirement of small perturbations to existing  software
     will be accepted.

          With this syntax, we introduce mechanisms so that:

          1. Users of mail systems can have multiple mailboxes, either
             on  one  machine  or  multiple machines, all of which are
             treated identically; the default mailbox for  a  user  is
             not  necessarily  associated  (directly)  with  his login
             name.

          2. Mail for a person can be sent to  other  than  a  single,
             default mailbox.

          3. Named   groups  may  consist  of  both  individuals   and
             (possibly)  other  named  groups  (i.e.,  nesting  within
             groups is permitted).

          4. Address lists may contain references  to  other,  stored,
             lists.  The complete path with which one can retrieve the
             stored list may be specified in  order  to  allow  either
             manual or automatic retrieval of the stored list.

          5. Address lists may contain references to  addresses  which
             are  not  accessible through the standard ARPANET message
             system.  For example, U.S.  Postal system  addresses  can
             be specified.  Such addresses are, of course, expected to
             be ignored by the  ARPANET  system,  although  individual
             sites  may  provide  services  for  using the information
             (e.g., automatically sending a copy of the  message to  a
             line printer, in preparation for transmission through the
             Postal system).

          6. Parenthetical remarks, or comments, can be  included  and
             syntactically  recognized  as  such  within  some  header
             items.

     I. Problems with ARPANET Message Standards                    / 5
     B. Issues and Conclusions

          7. Received messages are capable of  being  read  by  humans
             without  a  program having to parse the message (or parts
             of it) before presenting the message to the user; however
             there  is  sufficient  formal  syntax to enable a parsing
             program to modify the appearance and content of  material
             presented  to  users.   Although message-display software
             may   exercise   considerable   control   over    message
             appearance, the degree to which a message's actual format
             is  PLEASANT  for  humans  to  read   is   entirely   the
             responsibility of the message creation program.

     No mechanism for authentication is provided,  since  the  Network
     provides  no  mechanisms for enforcing mail security.  The syntax
     does provide for one aspect of "correctness":  a  distinction  is
     made  between  an  address which is claimed to be a valid network
     address and one which is  simply  free  text,  included  for  the
     convenience of the human participants.

     C. MESSAGE PARTS

          Some  confusion  has  existed  over  the  roles  played   by
     different message parts.  Einar Stefferud has suggested using the
     perspective of envelope, letter head, and  letter  content.   The
     presence of structured portions in messages additionally requires
     reference to "headers".

          In  computer-based  message  systems,  human  users  do  not
     generally  encounter  "envelopes",  which  are  often constructed
     automatically, to be  used  by  the  participating  system(s)  to
     deliver  the  message.  For example on TENEX, the envelope is the
     name of the file containing a message awaiting transmission.  For
     FTP  servers,  it is the data portion of the MAIL or MLFL command
     line.  Some systems attach  "envelope-like"  information  to  the
     message header, such as time-stamp and originating host name.

          In paper-based communications,  headers  occur  both  before
     (e.g., "To:" and "From:" and after (e.g., "cc:" and "enclosure:")
     the body of the message.  Within this standard, all headers occur
     before  the  body  of the message, although local message display
     programs may choose to alter that ordering.

          Wayne Hathaway has pointed out that ARPANET  message  format
     does not support specification of letterheads, since these are  a
     type   of   organizational   public   relations   symbol.    Some
     idiosyncrasies are supported, however, by way of choosing special
     field names.

          In general, it is  important  to  realize  that  the  header
     portion  of  a  message  plays several roles during the life of a

     I. Problems with ARPANET Message Standards                    / 6
     C. Message Parts

     message, variously participating in each of the  three  functions
     suggested by Stefferud.

     D. ADOPTION OF THE STANDARD

         During the early phases of specifying this standard, a  great
     deal  of  concern  was  expressed  over the problems which may be
     experienced during the transition from the  current  standard  to
     this  new  one.   We  feel  that  the true problem is the lack of
     realization that THERE IS NO CURRENT OFFICIAL  STANDARD.   Enough
     systems  have  enough  overlapping behaviors to allow the current
     mail environment to function, but this in no  way  constitutes  a
     standard.

          In fact, we  strongly  believe  that  the  new  requirements
     imposed by the proposed standard involve less complexity than the
     ambiguities resulting  from  the  current  variations  in  system
     behaviors.

     II. Standard for the Format of Messages                       / 7

                     II. STANDARD FOR THE FORMAT
                         OF ARPA NETWORK MESSAGES

          This standard supercedes the informal standards specified in
     ARPANET  Request for Comments numbers 561, "Standardizing Network
     Mail Headers", and 680, "Message Transmission Protocol".  In this
     document, a general framework is described.  The formal syntax is
     then specified,  followed  by  a  discussion  of  the  semantics.
     Finally, a number of examples are given.

          This specification is intended strictly as a  definition  of
     what is to be passed  between hosts  on the  ARPANET.   It is NOT
     intended to dictate either features which systems on the  Network
     are  expected  to support, or user interfaces to message creating
     or reading programs.

          A distinction should be made between what the  specification
     requires  and  what it allows.  Certain equivalences are defined,
     such as between a space  character  <space>  and  an  end-of-line
     character  <crlf>, which both facilitate the formal specification
     and indicate  what  the  OFFICIAL  semantics  are  for  messages.
     Particular   implementations   may   wish   to  preserve  further
     distinctions which the specification does not require.

     A. FRAMEWORK

          Since there are many message systems which exist outside the
     ARPANET environment, as well as those within it, it may be useful
     to consider the general framework, and resulting capabilities and
     limitations, of this standard.

          Messages are expected to  consist  of  lines  of  text.   No
     special provisions are made, at this time, for encoding drawings,
     facimile, speech, or structured text.

          No significant consideration has been given to questions  of
     data   compression   or   transmission/storage  efficiency.   The
     standard, in fact, tends to be very free with the number of  bits
     consumed.   For  example, field names are specified as free text,
     rather than special terse codes.

          A general "memo" framework is  used.   That  is,  a  message
     consists  of some information, in a rigid format, followed by the
     main part of the message, which is text  and whose format is  not

     II. Standard for the Format of Messages                       / 8
      A. Framework

     specified  in this document.  The syntax of several fields of the
     rigidly-formated  ("header")   section   is   defined   in   this
     specification;  some of the header fields must be included in all
     messages.  In addition to the fields specified in this  document,
     it  is  expected  that  other fields will gain common use.  User-
     defined header fields allow systems to extend their functionality
     while  maintaining  a uniform framework.  Our approach is similar
     to that of the TELNET protocol, in that we are defining  a  basic
     standard which includes a mechanism  for  (optionally)  extending
     itself.    The   authors  of  this  document  will  regulate  the
     publishing of specifications for these extensions.

          Such a framework severely  constrains  document  "tone"  and
     appearance  and  is  primarily useful for most intra-organization
     communications  and  relatively   structured   inter-organization
     communication.   A more robust environment might allow for multi-
     font, multi-color, multi-dimension encoding  of  information.   A
     less  robust  environment,  as  is present in most single-machine
     message systems, would more severely constrain the ability to add
     fields  and the decision to include specific fields.  Relative to
     paper-based communication, it is interesting  to  note  that  the
     RECEIVER  of  a  message  can exercise an extraordinary amount of
     control over the message's  appearance.   The  amount  of  actual
     control  available  to  message  receivers is contingent upon the
     capabilties of their individual message systems.

     II. Standard for the Format of Messages                       / 9
      B. Syntax

     B.  SYNTAX

          This  syntax  is  given  in  four  parts.   The  first  part
     describes  a  base-level lexical analyzer which feeds the higher-
     level parser described in the succeeding  sections.   The  second
     part  gives  a  general  syntax  for messages and standard header
     fields.  The third part specifies the  syntax  of  addresses.   A
     final  section  specifies  some general syntax which supports the
     other sections.

     1.  LEXICAL ANALYSIS OF MESSAGES

     a.  General Description

         A message consists of headers and, optionally, a  body  (i.e.
         the  <message-text>).   The  <message-text>  part  is  just a
         sequence of  ASCII  characters;  it  is  separated  from  the
         headers  by  a null line (i.e., a line with nothing preceding
         the <crlf>).

         1) Folding and unfolding of headers

            Each header item can be viewed as a single, logical,  long
            line   of   ASCII   characters.    For  convenience,  this
            conceptual  entity  can  be  split  into  a  multiple-line
            representation (i.e., "folded").  The general rule is that
            wherever there can be <linear-white-space> characters, you
            can  instead  insert  a  <crlf> immediately followed by AT
            LEAST  one  <linear-white-space>  character.   Thus,   the
            single line

               To:  "Joe Dokes & J. Harvey" <ddd at Host>, JJV at BBN

            can be represented as

               To:  "Joe Dokes & J. Harvey" <ddd at Host>,
                    JJV at BBN

            and

               To:  "Joe Dokes & J. Harvey"
                                <ddd at Host>,
                JJV at BBN

     II. Standard for the Format of Messages                      / 10
      B. Syntax
      1. Lexical Analysis

            and

               To:  "Joe Dokes
                & J. Harvey" <ddd at Host>, JJV at BBN

            The process  of  moving  from  this  folded  multiple-line
            representation  of  a  header  field  to  its  single line
            representation will be called "unfolding".   Unfolding  is
            accomplished by regarding <crlf> immediately followed by a
            <linear-white-space-char> as equivalent  to  the  <linear-
            white-space-char>.

         2) Structure of header fields

            Once header fields have been unfolded, they may be  viewed
            as  being  composed  of  a  <field-name> followed by a ":"
            (colon), followed by  a  <field-body>.   The  <field-name>
            must  be  composed  of  printable  ASCII characters (i.e.,
            characters which have decimal values between 33  and  126)
            and <linear-white-space> characters.  The <field-body> may
            composed of any ASCII  characters  (other  than  <cr>  and
            <lf>, which have been removed by unfolding).

            Certain header fields may be interpreted according  to  an
            internal  syntax  which  some  systems  may wish to parse.
            These fields will be referred  to  as  structured  fields.
            Examples  include  fields  containing dates and addresses.
            Other fields, such as  the  subject  field,  are  regarded
            simply as a single line of text.

         3) Field names

            To aid in the creation and reading of  <field-name>s,  the
            free   insertion  of  <linear-white-space>  characters  is
            allowed in reasonable places.  Rather than  obscuring  the
            syntax  specification  for  <field-name> with the explicit
            syntax  for  these  <linear-white-space>  characters,  the
            existence  of a simple "lexical" analyzer is assumed.  The
            analyzer reinterprets the unfolded  text  which  comprises
            the  <field-name>  as  a  sequence of <atoms> separated by
            <linear-white-space> characters.  The field  name  may  be
            conveniently  represented  by the sequence of these atoms,
            separated by a single ASCII space character.

     II. Standard for the Format of Messages                      / 11
      B. Syntax
      1. Lexical Analysis

         4) Field bodies

            To aid in the creation and reading  of  structured fields,
            the  free  insertion of <linear-white-space> characters is
            allowed in reasonable places.  Rather than  obscuring  the
            syntax specifications for  these  structured  fields  with
            explicit syntax for these <linear-white-space> characters,
            the existence of  another  simple  "lexical"  analyzer  is
            assumed.   It  provides  an interpretation of the unfolded
            text comprising the body of the field  as  a  sequence  of
            lexical symbols.  These include

                    -  individual special characters
                    -  quoted strings
                    -  comments
                    -  atoms

            The first three symbols are  self-delimiting.   Atoms  are
            not;  they  therefore are delimited by the self-delimiting
            symbols and by <linear-white-space>.

            So, for example, the folded body of an address field

                    ":sysmail"@ Some-Host,
                    Muhammed(I am the greatest)Ali at WBA

            is analyzed into the following lexical symbols and types:

                    ":sysmail"              quoted string
                    @                       special
                    Some-Host               atom
                    ,                       special
                    Muhammed                atom
                    (I am the greatest)     comment
                    Ali                     atom
                    at                      atom
                    WBA                     atom

     b.  Formal Definition

         <field>           ::=   <field-name> ":" <field-body>
         <field-name>      ::=   <atom>
                               | <atom> <field-name>

         <field-body>      ::=   <field-body-contents>
                               | <field-body-contents> <crlf>
                                    <linear-white-space-char>
                                    <field-body>

     II. Standard for the Format of Messages                      / 12
      B. Syntax
      1. Lexical Analysis

         <field-body-contents> ::= <the TELNET ASCII characters making
                                    up the <field-body>, as defined in
                                    the following sections, and
                                    consisting of combinations of
                                    <atom>, <quoted-string>, <text-line>,
                                    and <specials> tokens>

         <atom>            ::=   <a sequence of one or more TELNET
                                    ASCII alpha-numeric or graphics
                                    characters, excluding all control
                                    characters (those characters with
                                    a decimal value less than 33 or
                                    equal to 127) and <delimeters> >

         <quoted-string>   ::=   <double quote mark ("), decimal 34>
                                    <a sequence of one or more TELNET
                                    ASCII characters, where two
                                    adjacent quotes are treated as a
                                    single quote and part of the
                                    string> <">

         <text-line>        ::=   <a sequence of one or more TELNET
                                    ASCII characters excluding <cr>
                                    and <lf> >

         <message-text>     ::=   <a sequence of zero of more TELNET
                                    ASCII characters>

         <delimeters>      ::=   <specials> | <comment>
                               | <linear-white-space> | <crlf>

         <specials>        ::=   "(" | ")" | "<" | ">"
                               | "@" | "," | ";" | ":" | <">

         <comment>         ::=   "(" <TELNET ASCII characters, except
                                    <crlf> > ")"

         <linear-white-space>::= <linear-white-space-char>
                               | <linear-white-space-char>
                                    <linear-white-space>
         <linear-white-space-char>::=  <space> | <horizontal-tab>

         <space>           ::=   <TELNET ASCII space (decimal 32)>
         <tab>             ::=   <TELNET ASCII tab   (decimal  9)>
         <cr>              ::=   <TELNET ASCII carriage return
                                    (decimal 13)>
         <lf>              ::=   <TELNET ASCII line feed (decimal 10)>
         <crlf>            ::=   <TELNET ASCII carriage return/line
                                  feed (decimal 13, followed by
                                  decimal 10)>

     II. Standard for the Format of Messages                      / 13
      B. Syntax
      1. Lexical Analysis

     c.  Clarifications

         1) Comments

            Comments  may  appear   only   within   <field-body>s   of
            structured fields.   A  comment is any set of TELNET ASCII
            characters, which is not within a quoted string, and which
            is  enclosed in matching parentheses; parentheses nest, so
            that if a left paren occurs in  a  comment  string,  there
            must also be a matching right paren.

            Comments are NOT passed to the FTP server, as  part  of  a
            MAIL  or  MLFL command, since comments are not part of the
            "formal" address.

         2) "White space"

            Remember that in structured fields, MULTIPLE LINEAR  WHITE
            SPACE TELNET ASCII CHARACTERS (namely <tab>s and <space>s)
            ARE TREATED AS SINGLE SPACES AND MAY FREELY  SURROUND  ANY
            SYMBOL.   In  all  header  fields, at least one <space> is
            REQUIRED only at the beginning of folded lines.

            Writers of mail-sending (i.e.  header generating) programs
            should realize that there is no Network-wide definition of
            the  effect  of  <tab>  TELNET  ASCII  characters  on  the
            appearance of text at another Network host; therefore, the
            use of <tab>s in message  headers,  though  permitted,  is
            discouraged.

            Note that the contents of messages are required to conform
            with  TELNET  NVT conventions (e.g.  <cr> must be followed
            by either <lf>, making a <crlf>, or <null>, if the <cr> is
            to stand alone).

         3) Quoted strings

            Where  permitted  (i.e.,  in  structured  fields)   quoted
            strings  are  treated as a single symbol (i.e.  equivalent
            to an <atom> syntactically).  However, if  quoted  strings
            are  to  be  "folded" onto multiple lines, then the syntax
            for folding must be  adhered  to  (See  items  II.B.1.a.1,
            above,  and  II.B.1.c.6,  below.)  Note  that the official
            semantics do not  encounter  <crlf>s  in  quoted  strings,
            although  particular  parsing  programs  may  wish to note
            their presence.

     II. Standard for the Format of Messages                      / 14
      B. Syntax
      1. Lexical Analysis

         4) Bracketing characters

            There are two types of brackets which must be well nested:

                - Parentheses are used to indicate comments.

                - Angle brackets  ("<"  and  ">")  are  used
                  where  there is a question of the presence
                  of machine-usable code (e.g.  deliminating
                  mailboxes).

         5) Case independence of certain specials <atom>s

            It should be assumed by all  mail  reading  programs  that
            certain  <atom>s  can be represented in any combination of
            upper and lower case.  These are:

                - <field-name>s,
                - "File", in a <path>,
                - "at", in an <at-indicator>,
                - <host-name>s,
                - <day-of-week>s,
                - <string-month>s, and
                - <time-zone>s

            For example, the <field-name>s "From", "FROM", "from", and
            even "FroM" should all be treated identically.  Note that,
            at the level of this specification, case  IS  relevant  to
            other   <word>s   and   <text-line>s.   Also  see  Section
            II.C.1.a.4, below.

         6) Folding long lines

            Each header item (field of the message) may be represented
            on  exactly  one  line consisting of the name of the field
            and its body, and this  is  what  the  parser  sees.   For
            readability,  it  is  recommended  that  the  <field-body>
            portion of long header items  be  "folded"  onto  multiple
            lines of the actual header.

         7) Backspace characters

            Backspace TELNET ASCII characters (ASCII  BS,  decimal  8)
            may  be  included  in  <text-line>  and <quoted-string> to
            effect overstriking; however, any use of backspaces  which
            effects  an overstrike to the left of the beginning of the
            <text-line> or <quoted-string> is prohibited.

     II. Standard for the Format of Messages                      / 15
      B. Syntax
      2. Messages

     2.  GENERAL SYNTAX OF MESSAGES:

         NOTE: The syntax indicates that items  in  <required-headers>
         must  be  in  a  specific  order and precede all other header
         items.  Header fields, in fact, are NOT required to occur  in
         any  particular  order.  Required header items must be unique
         (occur exactly once).  This  specification  permits  multiple
         occurrences   of   most   optional   fields.    However,  the
         interpretation of such multiple occurrences is not  specified
         here.

         <message>         ::=   <headers>
                               | <headers> <crlf> <message-text>

         <headers>         ::=   <required-headers>
                               | <required-headers> <optional-headers>
         <required-headers> ::=  <date-field> <originator>
         <originator>      ::=   <mach-from-field>
                               | <mach-from-list> <sender-field>
                               | <mach-from-field> <reply-to-field>
                               | <any-from-field> <sender-field>
                                    <reply-to-field>

         <date-field>      ::=   "Date"        ":" <date-time>
         <mach-from-field> ::=   "From"        ":" <mach-addr-item>
         <mach-from-list>  ::=   "From"        ":" <mach-addr-list>
         <any-from-field>  ::=   "From"        ":" <address-list>
         <sender-field>    ::=   "Sender"      ":" <host-phrase>
         <reply-to-field>  ::=   "Reply-To"    ":" <mach-addr-list>

         <optional-headers>::=   <optional-header-field>
                               | <optional-headers>
                                    <optional-header-field>

         <optional-header-field> ::= <addressee-field>
                               | <extension-field>

         <addressee-field> ::=   "To"          ":" <address-list>
                               | "cc"          ":" <address-list>
                               | "bcc"         ":" <address-list>
                               | "Fcc"         ":" <path-list>

         <extension-field> ::=   "In-Reply-To" ":" <reference-list>
                               | "Keywords"    ":" <phrase-list>
                               | "Message-Id"  ":" <mach-host-phrase>
                               | "References"  ":" <reference-list>
                               | "Subject"     ":" <text-line>
                               | "Comments"    ":" <text-line>
                               | <user-defined-field>

     II. Standard for the Format of Messages                      / 16
      B. Syntax
      2. Messages

         <user-defined-field> ::= <A <field> which has a <field-name>
                                    not defined in this specification>

     The following syntax for the bodies of various fields  should  be
     thought  of as describing each field body as a single long string
     (or line).  The section  on  Lexical  Analysis  (section  II.B.1)
     indicated  how  such long strings can be represented on more than
     one line in the actual transmitted message.

     3.  SYNTAX OF GENERAL ADDRESSEE ITEMS

         <mach-addr-list>  ::=   <mach-addr-item>
                               | <mach-addr-item> "," <address-list>

         <address-list>    ::=   <null>
                               | <address-item>
                               | <address-item> "," <address-list>
         <address-item>    ::=   <mach-addr-item>
                               | <group-name> ":" <address-list> ";"
                               | <any-name>
                               | <path>

         <mach-addr-item>  ::=   <mailbox>
                               | <phrase> "<" <mailbox-list> ">"

         <group-name>      ::=   <phrase>
         <any-name>        ::=   <quoted-string>

         <mailbox-list>    ::=   <mailbox>
                               | <mailbox> "," <mailbox-list>
         <mailbox>         ::=   <host-phrase>

         <path>            ::=   ":" "File" ":" <path-name>
         <path-name>       ::=   <path-item>
                               | "<" <path-list> ">"
         <path-list>       ::=   <path-item>
                               | <path-item> "," <path-list>
         <path-item>       ::=   <host-phrase>

     II. Standard for the Format of Messages                      / 17
      B. Syntax
      4. Supporting Constructs

     4.  SUPPORTING SYNTAX

         <reference-list>  ::=   <null>
                               | <reference-item>
                               | <reference-item> "," <reference-list>
         <reference-item>  ::=   <phrase>
                               | <mach-host-phrase>

         <mach-host-phrase>::=   "<" <host-phrase> ">"
         <host-phrase>     ::=   <phrase> <host-indicator>
         <host-indicator>  ::=   <at-indicator> <host-name>
         <at-indicator>    ::=   "at" | "@"
         <host-name>       ::=   <atom>
                               | <decimal host address>

         <date-time>       ::=   <day> <date> <time>
         <day>             ::=   <null>
                               | <day-of-week> ","
         <day-of-week>     ::=   "Monday"    | "Mon"
                               | "Tuesday"   | "Tue"
                               | "Wednesday" | "Wed"
                               | "Thursday"  | "Thu"
                               | "Friday"    | "Fri"
                               | "Saturday"  | "Sat"
                               | "Sunday"    | "Sun"
         <date>            ::=   <string-date>
                               | <slash-date>
         <string-date>     ::=   <day-of-month> <string-month>
                                                <4-digit-year>
         <slash-date>      ::=   <numeric-month> "/" <date-of-month>
                                                 "/" <2-digit-year>
         <numeric-month>   ::=   <one or two decimal digits>
         <day-of-month>    ::=   <one or two decimal digits>
         <string-month>    ::=   "January" | "Jan"
                               | "February" | "Feb"
                               | "March"    | "Mar"
                               | "April"    | "Apr"
                               | "May"
                               | "June"     | "Jun"
                               | "July"     | "Jul"
                               | "August"   | "Aug"
                               | "September"| "Sep"
                               | "October"  | "Oct"
                               | "November" | "Nov"
                               | "December" | "Dec"
         <4-digit-year>    ::=   <four decimal digits>
         <2-digit-year>    ::=   <two decimal digits>
         <time>            ::=   <24-hour-time> "-" <time-zone>
         <24-hour-time>    ::=   <hour> <minute>
         <hour>            ::=   <two decimal digits>
         <minute>          ::=   <two decimal digits>

     II. Standard for the Format of Messages                      / 18
      B. Syntax
      4. Supporting Constructs

         <time-zone>       ::=   "GMT" | "Z"   | "GDT"
                               | "AST" | "ADT"
                               | "EST" | "EDT" | "CST" | "CDT"
                               | "MST" | "MDT" | "PST" | "PDT"
                               | "YST" | "YDT" | "HST" | "HDT"

         <phrase>          ::=   <word>
                               | <word> <phrase>
         <phrase-list>     ::=   <null>
                               | <phrase>
                               | <phrase> "," <phrase-list>

         <word>            ::=   <atom>
                               | <quoted-string>

     II. Standard for the Format of Messages                      / 19
      C. Semantics
      1. Address Fields

     C. SEMANTICS

     1. ADDRESS FIELDS

     a. General

        1) <path>s are used to refer to a location,  on  the  ARPANET,
           containing  a  stored  address  list.   The <phrase> should
           contain text which the referenced host  can  resolve  to  a
           file.   This  standard  is  not  a protocol and so does not
           prescribe HOW data  is  to  be  retrieved  from  the  file.
           However, the following requirements are made:

           - the   file  must  be  accessible  through  the   local
             operating  system  interface  (if  it  exists),  given
             adequate user access rights; and

           - if a host has an FTP server and  a  user  is  able  to
             retrieve  any  files  from the host using that server,
             then the file must be accessible  through  FTP,  using
             DEFAULT  transfer settings, given adequate user access
             rights.

           It is intended that this mechanism will allow  programs  to
           retrieve such lists automatically.

           The interpretation  of  a  <path>  follows.   This  is  not
           intended to imply any particular implementation scheme, but
           is included to aid in understanding the notion of <path>s:

           - The contents of the file indicated by a <path-name> is
             treated  as  an  <address-list>  and is inserted as an
             <address-item> in the position of the <path-name> item
             in  the  syntax.   That is, the TELNET ASCII character
             string of the <path-name> or, if present,  the  <path-
             list>  containing  it,  is replaced by the contents of
             the file to which the <path-name>  refers.  Therefore,
             the  contents  of  the file indicated by a <path-name>
             must be syntactically self-contained and  must  adhere
             to  the  full  syntax  prescribed herein for <address-
             list>.

           - <Path-item>s of a <path-list> are alternates  and  the
             contents  of ONLY ONE of them is to be included in the
             resultant address list.

        2) The <phrase> part  of  a  <mailbox>  is  understood  to  be
           whatever  the  receiving  FTP  Server  allows (for example,

     II. Standard for the Format of Messages                      / 20
      C. Semantics
      1. Address Fields

           TENEX systems do not now understand addresses of  the  form
           "P.  D.  Q.  Bach", but another system might).

           Note that a <mailbox> is a conceptual entity which does not
           necessarily  pertain  to  file  storage.  For example, some
           sites may choose to print mail on their  line  printer  and
           deliver the output to the addressee's desk.

           A user may have several mailboxes. The use  of  the  second
           alternative  of  <mach-addr-item>  (<phrase>  "<" <mailbox-
           list> ">") indicates that a copy of the message  is  to  be
           sent to EACH mailbox named.

        3) <any-name>  may  contain  any  sequence  of  "words".  This
           sequence  of  words,  used as an <address-item>, is used to
           facilitate reference  to  non-standard  (e.g.  non-Network)
           addresses.    Such   an  address  might  be  one  which  is
           acceptable to the U.S.  Postal Service.

        4) The <host-name> in a <host-phrase>  must  be  THE  official
           name of a Network host, or else a decimal number indicating
           the Network address for that host.  The USE OF  NUMBERS  IS
           STRONGLY  DISCOURAGED  and  is  permitted  only  due to the
           occasional necessity of bypassing local host-name tables.

           The  <phrase>  in  a  <host-phrase>  is  intended   to   be
           meaningful only to the indicated host.  To all other hosts,
           the <phrase> is treated  as  a  literal  string.   No  case
           transformations  should be (automatically) performed on the
           <phrase>.  The <phrase> is passed to the local host's  mail
           sending   program;   it   is   the  responsibility  of  the
           destination host's mail receiving (distribution) program to
           perform  case  mapping  on  this  <phrase>, if required, to
           deliver the mail.

     b. Originator Fields

           WARNING: The standard allows only a subset of  the
                    combinations   possible  with  the  From,
                    Sender,   and   Reply-to   fields.    The
                    limitation  is intentional; the permitted
                    alternatives have been  carefully  chosen
                    and are adequate for the purposes of this
                    standard.

     II. Standard for the Format of Messages                      / 21
      C. Semantics
      1. Address Fields

        1) From:

           This field contains  the  identity  of  the  person(s)  who
           wished  this  message  to  be  sent.   The message-creation
           process should default this field to be  a  single  machine
           address,  indicating  the user entering the message; if and
           only if this is done,  the  "Sender:"  field  need  not  be
           present.

        2) Sender:

           This field contains the identity of the  person  who  sends
           the  message.   It need not be present in the header of the
           message if it is the SAME as the "From:" field.

           The <sender-field-body>  includes  a  <phrase>  which  must
           correspond  to  a  user,  rather  than a standard <address-
           item>, to indicate the  expectation  that  the  field  will
           refer  to  the  PERSON responsible for sending the mail and
           not simply include the name of a mailbox,  from  which  the
           mail  was  sent.  For example in the case of a shared login
           name, the name, by itself,  would  not  be  adequate.   The
           <phrase>  (user)  is  a  system  entity,  not a generalized
           person reference.

        3) Reply-to:

           This field provides a general mechanism for indicating  any
           mailbox(es)  to  which  responses  are  to  be sent.  Three
           different uses for this feature can be  distinguished.   In
           the  first  case,  the  author(s)  may  not  have   regular
           machine-based  mailboxes  and therefore wish to indicate an
           alternate machine address.  In the second case,  an  author
           may  wish  additional  persons  to  be  made  aware  of, or
           responsible for, responses; responders  should  send  their
           replies  to  the "Reply-to:" mailbox(es).  More interesting
           is a case such as text-message teleconferencing in which an
           automatic distribution facility  is  provided  and  a  user
           submitting  an  "entry" for distribution only needs to send
           their message to the mailbox(es) indicated in  the  "Reply-
           to:" field.

           If there is no <reply-to-field>, then the <from-field> MUST
           contain  AT  LEAST  ONE machine address.  In all cases when
           used and even if a <sender> field is present, the  Reply-to
           field must contain at least one machine address.

        NOTE: For systems which automatically generate  address  lists
        for replies to messages, the following requirements are made:

     II. Standard for the Format of Messages                      / 22
      C. Semantics
      1. Address Fields

           - The receiver, when replying to a message,  must  NEVER
             automatically  include  the <sender-field-body> in the
             reply's address list

           - If the <reply-to-field> exists, then the reply  should
             go ONLY to the <reply-to-field-body> addressees.

        (Extensive  examples  are  provided  in  Section  II.D.)  This
        recommendation is intended only for <originator-field>s and in
        no way is intended to reflect that replies should not be sent,
        also,  to  the  other recipients of this message.  It is up to
        the respective mail handling programs as  to  what  additional
        facilities will be provided.

     c. Receiver Fields

        1) To:

           This field contains the identity of the primary  recipients
           of the message.

        2) cc:

           This  field  contains  the  identity   of   the   secondary
           recipients of the message.

        3) Bcc:

           This field contains the identity of  additional  recipients
           of  the  message  who are to remain hidden from the primary
           and secondary  recipients.   Some  systems  may  choose  to
           include   the   text  of  the  "Bcc:"  field  only  in  the
           author(s)'s copy, while others may include it in  the  text
           sent to all those indicated in the "Bcc:" list.

        4) Fcc:

           This field contains the identity of any  message  files  in
           which  copies  of  this  message  are  being  placed by the
           originator.  Note that the presence of this field does  NOT
           guarantee  long-term  availability of the message in any of
           the indicated files.

     II. Standard for the Format of Messages                      / 23
      C. Semantics
      2. Reference Specification Fields

     2. REFERENCE SPECIFICATION FIELDS

     a. Message-Id:

        This field contains a  unique  identifier  (the  <phrase>)  to
        refer  to this version of this message.  The uniqueness of the
        message  identifier  is  guaranteed  by   each   host.    This
        identifier  is  intended  to  be  machine  readable,  and  not
        necessarily meaningful to humans.  A  message-id  pertains  to
        exactly  one instantiation of a particular message; subsequent
        revisions to the message should receive new message-id's.

     b. In-Reply-To:

        The contents of this field  identify  previous  correspondence
        which  this  message answers.  If message identifiers are used
        in this field, they should be enclosed in angle brackets (<>).

     c. References:

        The contents of this field identify other correspondence which
        this  message  references.   If  message identifiers are used,
        they should be enclosed in angle brackets (<>).

     d. Keywords:

        This field contains keywords or phrases, separated by commas.

     3. OTHER FIELDS AND SYNTACTIC ITEMS

     a. Subject:

        The  "subject:"  field  is  intended  to   provide   as   much
        information  as  necessary to adequately summarize or indicate
        the nature of the message.

     b. Comments:

        Permits  adding  text  comments  onto  the   message   without
        disturbing the contents of the message's body.

     II. Standard for the Format of Messages                      / 24
      C. Semantics
      4. Dates

     4. DATES

        It is recommended that,  because  of  differing  international
        interpretations,  the  <string-day>  option be used instead of
        the <slash-day> option in the specification of a <day>.

        If included, <day-of-week> must be  the  day  implied  by  the
        <date> specification.

        <Time-zones> allow reference to Greenwich and to each  of  the
        zones  in  the  United  States.  The zone references beginning
        with "A" are for Atlantic time which are one hour faster  than
        the  corresponding Eastern times.  "Y" indicates Yukon time in
        Alaska, which  is  one  hour  slower  than  the  corresponding
        Pacific times, and "H" indicates Hawaiian times, which are two
        hours slower.

     II. Standard for the Format of Messages                      / 25
      D. Examples

     D. EXAMPLES

     1. ADDRESSES

     a. Alfred E. Newman <Newman at BBN-TENEXA>
        Newman@BBN-TENEXA

        These  two  "Alfred  E.   Newman"  examples   have   identical
        semantics,  as far as the operation of the local host's mailer
        and the remote host's FTP server are concerned.  In the  first
        example,  the "Alfred E.  Newman" is ignored by the mailer, as
        "Newman at BBN-TENEXA"  completely  specifies  the  recipient.
        The  second  example contains no superfluous information, and,
        again, "Newman@BBN-TENEXA" is the intended recipient.

     b. Al Newman at BBN-TENEXA

        This is identical with "Al Newman<Al Newman  at  BBN-TENEXA>."
        That is, the full <phrase>, "Al Newman", is passed to the  FTP
        server.   Note  that  not  all  FTP  servers accept multi-word
        identifiers; and some that do accept them will treat each word
        as  a  different addressee (in this case, attempting to send a
        copy of the message to "Al" and a copy to "Newman").

     c. "George Lovell, Ted Hackle" <Shared-Mailbox at Office-1>

        This form might be used to indicate that a single  mailbox  is
        shared  by several users.  The quoted string is ignored by the
        originating host's mailer,  as  "Shared-Mailbox  at  Office-1"
        completely specifies the destination mailbox.

     d. Wilt (the Stilt) Chamberlain at NBA

        The "(the Stilt)" is a comment, which is NOT included  in  the
        destination mailbox address handed to the originating system's
        mailer.  The address is the string  "Wilt  Chamberlain",  with
        exactly  one  space  between the first and second words.  (The
        quotation marks are not included.)

     II. Standard for the Format of Messages                      / 26
      D. Examples

     2. ADDRESS LISTS

            Gourmets:  Pompous Person <WhoZiWhatZit at Cordon-Bleu>,
                       Cooks:  Childs at WGBH, Galloping Gourmet at
                               ANT (Australian National Television);
                       Wine Lovers:  Drunk at Discount-Liquors,
                                     Port at Portugal;;,
            Jones at SEA

        This group list example points out the use  of  comments,  the
        nesting  of  groups,  and  the mixing of addresses and groups.
        Note that the two consecutive semi-colons  preceding "Jones at
        SEA" mean that Jones is NOT a member of the Gourmets group.

     3. ORIGINATOR ITEMS

     a. George Jones logs into his Host as  "Jones".   He  sends  mail
        himself.

            From:  Jones at Host
        or
            From:  George Jones <Jones at Host>

     b. George Jones logs in as Jones on his Host.  His secretary, who
        logs  in  as  Secy  on  her  Host  (SHost) sends mail for him.
        Replies to the mail should go to George, of course.

            From:    George Jones <Jones at Host>
            Sender:  Secy at SHost

     c. George Jones logs in as Group at Host.  He sends mail himself;
        replies should go to the Group mailbox.

            From:  George Jones <Group at Host>

     d. George Jones' secretary sends mail for George in his  capacity
        as a member of Group while logged in as Secy at Host.  Replies
        should go to Group.

            From:   George Jones<Group at Host>
            Sender: Secy at Host

        Note that there need not be a space between  "Jones"  and  the
        "<",  but  adding a space enhances readability (as is the case
        in other examples).

     e. George Jones asks his secretary  (Secy  at  Host)  to  send  a
        message  for  him  in  his  capacity  as  Group.  He wants his
        secretary to handle all replies.

     II. Standard for the Format of Messages                      / 27
      D. Examples

            From:     George Jones <Group at Host>
            Sender:   Secy at Host
            Reply-to: Secy at Host

     f. A non-ARPANET user friend  of  George's,  Sarah,  is  visting.
        George's  secretary  sends  some  mail to a friend of Sarah in
        computer-land.  Replies should go to George, whose mailbox  is
        Jones at Host.

            From:     Sarah Friendly
            Sender:   Secy at Host
            Reply-to: Jones at Host

     g. George is a member of a committee.   He  wishes  to  have  any
        replies to his message go to all committee members.

            From:     George Jones
            Sender:   Jones at Host
            Reply-To: Big-committee: Jones at Host,
                                     Smith at Other-Host,
                                     Doe at Somewhere-Else;

        Note  that  if  George  had  not  included  himself   in   the
        enumeration  of  Big-committee,  he  would  not  have gotten a
        reply; the presence of the "Reply-to:"  field  SUPERSEDES  the
        sending of a reply to the person named in the "From:" field.

     h. (Example of INCORRECT USE)

        George desires a reply to go to his secretary;  therefore  his
        secretary  leaves  his  mailbox address off the "From:" field,
        leaving only  his  name,  which  is  not,  itself,  a  mailbox
        address.

                 From:   George Jones
                 Sender: Secy at SHost

        THIS IS NOT PERMITTED.  Replies are NEVER implicitly  sent  to
        the   "Sender:";  George's  secretary  should  have  used  the
        "Reply-to:" field, or the mail creating program she was  using
        should have forced her to.

     i. George's secretary sends out  a  message  which  was  authored
        jointly by all the members of the "Big-committee".

            From:   Big-committee: Jones at Host,
                                   Smith at Other-Host,
                                   Doe at Somewhere-Else;
            Sender: Secy at SHost

     II. Standard for the Format of Messages                      / 28
      D. Examples

     4. COMPLETE HEADERS

     a. Minimum required:

            Date:  26 August 1976 1429-EDT
            From:  Jones at Host

     b. Using some of the additional fields:

            Date  26 August 1976 1430-EDT
            From:  George Jones<Group at Host>
            Sender: Secy at SHOST
            To:    Al Newman at Mad-Host,
                   Sam Irving at Other-Host
            Message-id:  some string at SHOST

     c. About as complex as you're going to get:

            Date:       27 Aug 1976 0932-PDT
            From:       Ken Davis <KDavis at Other-Host>
            Sender:     KSecy at Other-Host
            Reply-to:   Sam Irving at Other-Host
            Subject:    Re: The Syntax in the RFC
            To:         George Jones <Group at Host>,
                        Al Newman at Mad-Host
            cc:         Tom Softwood <Balsa at Another-Host>,
                        Sam Irving at Other-Host,
                        Standard Distribution:
                         :File:
                           </main/davis/people/standard at Other Host,
                           "<Jones>standard.dist.3" at Tops-20-Host>
            In-Reply-to: <some string at SHOST>
            Message-ID: 4231.629.XYzi-What at Other-Host
            Comment:    Sam is away on business. He asked me to handle
                        his  mail  for  him  today.   He'll be able to
                        provide a more accurate  explanation  tomorrow
                        when he returns.

     III. References

                            III.  REFERENCES

     --- TELNET Protocol Specification.   Network  Information  Center
        No.  18639;  Augmentation  Research  Center, Stanford Research
        Institute: Menlo Park, August 1973.

     Bhushan, A.K.  The File Transfer Protocol.  ARPANET  Request  for
        Comments,  No.   354,  Network  Information Center No.  10596;
        Augmentation Research  Center,  Stanford  Research  Institute:
        Menlo Park, July 1972.

     Bhushan, A.K.  Comments on the File Transfer  Protocol.   ARPANET
        Request for Comments, No.  385, Network Information Center No.
        11357;  Augmentation  Research   Center,   Stanford   Research
        Institute: Menlo Park, August 1972.

     Bhushan, A.K., Pogran, K.T., Tomlinson,  R.S.,  and  White,  J.E.
        Standardizing  Network  Mail  Headers.   ARPANET  Request  for
        Comments, No.  561,  Network  Information  Center  No.  18516;
        Augmentation  Research  Center,  Stanford  Research Institute:
        Menlo Park, September 1973.

     Feinler,  E.J.  and  Postel,  J.B.   ARPANET  Protocol  Handbook.
        Network  Information  Center  No.  7104; Augmentation Research
        Center, Stanford Research Institute: Menlo Park,  April  1976.
        (NTIS AD A003890).

     McKenzie,  A.   File  Transfer  Protocol.   ARPANET  Request  for
        Comments,  No.  454,  Network  Information  Center  No. 14333;
        Augmentation Research  Center,  Stanford  Research  Institute:
        Menlo Park, February 1973.

     Myer, T.H. and Henderson, D.A.   Message  Transmission  Protocol.
        ARPANET  Request  for  Comments,  No. 680, Network Information
        Center  No.  32116;  Augmentation  Research  Center,  Stanford
        Research Institute: Menlo Park, 1975.

     Neigus,  N.   File  Transfer  Protocol.   ARPANET   Request   for
        Comments,  No.  542,  Network  Information  Center  No. 17759;
        Augmentation Research  Center,  Stanford  Research  Institute:
        Menlo Park, July 1973.

     Postel, J.B.  Revised  FTP  Reply  Codes.   ARPANET  Request  for
        Comments,  No.  640,  Network  Information  Center  No. 30843;
        Augmentation Research  Center,  Stanford  Research  Institute:
        Menlo Park, June 1974.

     Appendix                                                     / 30
     Alphabetical Listing of Syntax Rules

                             APPENDIX

     A.  ALPHABETICAL LISTING OF SYNTAX RULES

     <2-digit-year>    ::=   <two decimal digits>
     <4-digit-year>    ::=   <four decimal digits>
     <24-hour-time>    ::=   <hour> <minute>

     <addressee-field> ::=   "To"          ":" <address-list>
                           | "cc"          ":" <address-list>
                           | "bcc"         ":" <address-list>
                           | "Fcc"         ":" <path-list>
     <address-item>    ::=   <mach-addr-item>
                           | <group-name> ":" <address-list> ";"
                           | <any-name>
                           | <path>
     <address-list>    ::=   <null> | <address-item>
                           | <address-item> "," <address-list>

     <any-from-field>  ::=   "From"        ":" <address-list>

     <any-name>        ::=   <quoted-string>

     <at-indicator>    ::=   "at" | "@"

     <atom>            ::=   <a sequence of one or more TELNET ASCII
                                alpha-numeric or graphics characters,
                                excluding all control characters
                                (those characters with a decimal value
                                less than 33 or equal to 127) and
                                <delimeters> >

     <comment>         ::=   "(" <TELNET ASCII characters, except
                                <crlf> > ")"

     <cr>              ::=   <TELNET ASCII carriage return (decimal 13)>
     <crlf>            ::=   <TELNET ASCII carriage return/line feed
                                (decimal 13, followed by decimal 10)>

     <date>            ::=   <string-date> | <slash-date>
     <date-field>      ::=   "Date"        ":" <date-time>
     <date-time>       ::=   <day> <date> <time>
     <day>             ::=   <null> | <day-of-week> ","
     <day-of-month>    ::=   <one or two decimal digits>
     <day-of-week>     ::=   "Monday"    | "Mon"
                           | "Tuesday"   | "Tue"
                           | "Wednesday" | "Wed"
                           | "Thursday"  | "Thu"

     Appendix                                                     / 31
     Alphabetical Listing of Syntax Rules

                           | "Friday"    | "Fri"
                           | "Saturday"  | "Sat"
                           | "Sunday"    | "Sun"

     <delimeter>       ::=   <specials> | <comment>
                           | <linear-white-space> | <crlf>

     <field>           ::=   <field-name> ":" <field-body>
     <field-body>      ::=   <field-body-contents>
                           | <field-body-contents> <crlf>
                                <linear-white-space-CHAR> <field-body>
     <field-body-contents> ::= <the TELNET ASCII characters making up
                                the field body, as defined in the
                                following sections and consisting of
                                combinations of <atom>, <quoted-
                                string>, <text-line>, and <specials>
                                tokens>

     <field-name>      ::=   <atom> | <atom> <field-name>

     <group-name>      ::=   <phrase>

     <headers>         ::=   <required-headers>
                           | <required-headers> <optional-headers>

     <host-indicator>  ::=   <at-indicator> <host-name>
     <host-name>       ::=   <atom>  | <decimal host address>
     <host-phrase>     ::=   <phrase> <host-indicator>

     <hour>            ::=   <two decimal digits>

     <lf>              ::=   <TELNET ASCII line feed (decimal 10)>
     <linear-white-space>::= <linear-white-space-char>
                           | <linear-white-space-char>
                                <linear-white-space>
     <linear-white-space-char>::=  <space> | <horizontal-tab>

     <mach-addr-item>  ::=   <mailbox> | <phrase> "<" <mailbox-list> ">"
     <mach-addr-list>  ::=   <mach-addr-item>
                           | <mach-addr-item> "," <address-list>

     <mach-from-field> ::=   "From"        ":" <mach-addr-item>
     <mach-from-list>  ::=   "From"        ":" <mach-addr-list>

     <mach-host-phrase>::=   "<" <host-phrase> ">"

     <mailbox>         ::=   <host-phrase>
     <mailbox-list>    ::=   <mailbox> | <mailbox> "," <mailbox-list>

     <message>         ::=   <headers>
                           | <headers> <crlf> <message-text>

     Appendix                                                     / 32
     Alphabetical Listing of Syntax Rules

     <message-text>    ::=   <a sequence of zero of more TELNET ASCII
                                characters>

     <minute>          ::=   <two decimal digits>

     <numeric-month>   ::=   <one or two decimal digits>

     <optional-headers>::=   <optional-header-field>
                           | <optional-headers> <optional-header-field>
     <optional-header-field> ::= <addressee-field> | <extension-field>

     <originator>      ::=   <mach-from-field>
                           | <mach-from-list> <sender-field>
                           | <mach-from-field> <reply-to-field>
                           | <any-from-field> <sender-field>
                                <reply-to-field>

     <path>            ::=   ":" "File" ":" <path-name>
     <path-item>       ::=   <host-phrase>
     <path-list>       ::=   <path-item> | <path-item> "," <path-list>
     <path-name>       ::=   <path-item> | "<" <path-list> ">"

     <phrase>          ::=   <word> | <word> <phrase>
     <phrase-list>     ::=   <null> | <phrase>
                           | <phrase> "," <phrase-list>

     <reference-item>  ::=   <phrase> | <mach-host-phrase>
     <reference-list>  ::=   <null> | <reference-item>
                           | <reference-item> "," <reference-list>

     <quoted-string>   ::=   <double quote mark ("), decimal 34>
                                <a sequence of one or more TELNET
                                ASCII characters, where two adjacent
                                quotes are treated as a single quote
                                and part of the string> <">

     <reply-to-field>  ::=   "Reply-To"    ":" <mach-addr-list>

     <required-headers> ::=  <date-field> <originator>

     <sender-field>    ::=   "Sender"      ":" <host-phrase>

     <slash-date>      ::=   <numeric-month> "/" <date-of-month>
                                             "/" <2-digit-year>
     <space>           ::=   <TELNET ASCII space (decimal 32)>

     <specials>        ::=   "(" | ")" | "<" | ">"
                           | "@" | "," | ";" | ":" | <">

     <string-date>     ::=   <day-of-month> <string-month>
     <string-month>    ::=   "January"  | "Jan" | "February" | "Feb"

     Appendix                                                     / 33
     Alphabetical Listing of Syntax Rules

                           | "March"    | "Mar" | "April"    | "Apr"
                           | "May"              | "June"     | "Jun"
                           | "July"     | "Jul" | "August"   | "Aug"
                           | "September"| "Sep" | "October"  | "Oct"
                           | "November" | "Nov" | "December" | "Dec"

     <tab>             ::=   <TELNET ASCII tab   (decimal  9)>

     <text-line>        ::=   <a sequence of one or more TELNET ASCII
                                characters excluding <cr> and <lf> >

     <time>            ::=   <24-hour-time> "-" <time-zone>
     <time-zone>       ::=   "GMT" | "Z"   | "GDT" | "AST" | "ADT
                           | "EST" | "EDT" | "CST" | "CDT"
                           | "MST" | "MDT" | "PST" | "PDT"
                           | "YST" | "YDT" | "HST" | "HDT"

     <user-defined-field> ::= <A <field> which has a <field-name> not
                                defined in this specification>

     <word>            ::=   <atom> | <quoted-string>

  ------------------------------------------------------------------------
             [ Index | Search | What's New | Comments | Help ]

  Comments/Questions about this archive ? Send mail to rfc-admin@faqs.org
