C.  DIFFERENCES FROM RFC #733

          The following summarizes the differences between this  stan-
     dard  and the one specified in Arpanet Request for Comments #733,
     "Standard for the Format of ARPA  Network  Text  Messages".   The
     differences  are  listed  in the order of their occurrence in the
     current specification.

     C.1.  FIELD DEFINITIONS

     C.1.1.  FIELD NAMES

        These now must be a sequence of  printable  characters.   They
        may not contain any LWSP-chars.

     C.2.  LEXICAL TOKENS

     C.2.1.  SPECIALS

        The characters period ("."), left-square  bracket  ("["),  and
        right-square  bracket ("]") have been added.  For presentation
        purposes, and when passing a specification to  a  system  that
        does  not conform to this standard, periods are to be contigu-
        ous with their surrounding lexical tokens.   No  linear-white-
        space  is  permitted  between them.  The presence of one LWSP-
        char between other tokens is still directed.

     C.2.2.  ATOM

        Atoms may not contain SPACE.

     C.2.3.  SPECIAL TEXT

        ctext and qtext have had backslash ("\") added to the list  of
        prohibited characters.

     C.2.4.  DOMAINS

        The lexical tokens  <domain-literal>  and    have  been
        added.

     C.3.  MESSAGE SPECIFICATION

     C.3.1.  TRACE

        The "Return-path:" and "Received:" fields have been specified.





     August 13, 1982              - 41 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


     C.3.2.  FROM

        The "From" field must contain machine-usable addresses  (addr-
        spec).   Multiple  addresses may be specified, but named-lists
        (groups) may not.

     C.3.3.  RESENT

        The meta-construct of prefacing field names  with  the  string
        "Resent-"  has been added, to indicate that a message has been
        forwarded by an intermediate recipient.

     C.3.4.  DESTINATION

        A message must contain at least one destination address field.
        "To" and "CC" are required to contain at least one address.

     C.3.5.  IN-REPLY-TO

        The field-body is no longer a comma-separated list, although a
        sequence is still permitted.

     C.3.6.  REFERENCE

        The field-body is no longer a comma-separated list, although a
        sequence is still permitted.

     C.3.7.  ENCRYPTED

        A field has been specified that permits  senders  to  indicate
        that the body of a message has been encrypted.

     C.3.8.  EXTENSION-FIELD

        Extension fields are prohibited from beginning with the  char-
        acters "X-".

     C.4.  DATE AND TIME SPECIFICATION

     C.4.1.  SIMPLIFICATION

        Fewer optional forms are permitted  and  the  list  of  three-