For  example  when  the local-part of an addr-spec must
               contain a special character, a quoted  string  must  be
               used.  Therefore, a specification such as:

                            Full\ Name@Domain

               is not legal and must be specified as:

                            "Full Name"@Domain


     August 13, 1982              - 11 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


     3.4.2.  WHITE SPACE

        Note:  In structured field bodies, multiple linear space ASCII
               characters  (namely  HTABs  and  SPACEs) are treated as
               single spaces and may freely surround any  symbol.   In
               all header fields, the only place in which at least one
               LWSP-char is REQUIRED is at the beginning of  continua-
               tion lines in a folded field.

        When passing text to processes  that  do  not  interpret  text
        according to this standard (e.g., mail protocol servers), then
        NO linear-white-space characters should occur between a period
        (".") or at-sign ("@") and a .  Exactly ONE SPACE should
        be used in place of arbitrary linear-white-space  and  comment
        sequences.

        Note:  Within systems conforming to this standard, wherever  a
               member of the list of delimiters is allowed, LWSP-chars
               may also occur before and/or after it.

        Writers of  mail-sending  (i.e.,  header-generating)  programs
        should realize that there is no network-wide definition of the
        effect of ASCII HT (horizontal-tab) characters on the  appear-
        ance  of  text  at another network host; therefore, the use of
        tabs in message headers, though permitted, is discouraged.

     3.4.3.  COMMENTS

        A comment is a set of ASCII characters, which is  enclosed  in
        matching  parentheses  and which is not within a quoted-string
        The comment construct permits message originators to add  text
        which  will  be  useful  for  human readers, but which will be
        ignored by the formal semantics.  Comments should be  retained
        while  the  message  is subject to interpretation according to
        this standard.  However, comments  must  NOT  be  included  in
        other  cases,  such  as  during  protocol  exchanges with mail
        servers.

        Comments nest, so that if an unquoted left parenthesis  occurs
        in  a  comment  string,  there  must  also be a matching right
        parenthesis.  When a comment acts as the delimiter  between  a
        sequence of two lexical symbols, such as two atoms, it is lex-
        ically equivalent with a single SPACE,  for  the  purposes  of
        regenerating  the  sequence, such as when passing the sequence
        onto a mail protocol server.  Comments are  detected  as  such
        only within field-bodies of structured fields.

        If a comment is to be "folded" onto multiple lines,  then  the
        syntax  for  folding  must  be  adhered to.  (See the "Lexical


     August 13, 1982              - 12 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


        Analysis of Messages" section on "Folding Long Header  Fields"
        above,  and  the  section on "Case Independence" below.)  Note
        that  the  official  semantics  therefore  do  not  "see"  any
        unquoted CRLFs that are in comments, although particular pars-
        ing programs may wish to note their presence.  For these  pro-
        grams,  it would be reasonable to interpret a "CRLF LWSP-char"
        as being a CRLF that is part of the comment; i.e., the CRLF is
        kept  and  the  LWSP-char is discarded.  Quoted CRLFs (i.e., a
        backslash followed by a CR followed by a  LF)  still  must  be
        followed by at least one LWSP-char.

     3.4.4.  DELIMITING AND QUOTING CHARACTERS

        The quote character (backslash) and  characters  that  delimit
        syntactic  units  are not, generally, to be taken as data that
        are part of the delimited or quoted unit(s).   In  particular,
        the   quotation-marks   that   define   a  quoted-string,  the
        parentheses that define  a  comment  and  the  backslash  that
        quotes  a  following  character  are  NOT  part of the quoted-
        string, comment or quoted character.  A quotation-mark that is
        to  be  part  of  a quoted-string, a parenthesis that is to be
        part of a comment and a backslash that is to be part of either
        must  each be preceded by the quote-character backslash ("\").
        Note that the syntax allows any character to be quoted  within