a  quoted-string  or  comment; however only certain characters
        MUST be quoted to be included as data.  These  characters  are
        the  ones that are not part of the alternate text group (i.e.,
        ctext or qtext).

        The one exception to this rule  is  that  a  single  SPACE  is
        assumed  to  exist  between  contiguous words in a phrase, and
        this interpretation is independent of  the  actual  number  of
        LWSP-chars  that  the  creator  places  between the words.  To
        include more than one SPACE, the creator must make  the  LWSP-
        chars be part of a quoted-string.

        Quotation marks that delimit a quoted string  and  backslashes
        that  quote  the  following character should NOT accompany the
        quoted-string when the string is passed to processes  that  do
        not interpret data according to this specification (e.g., mail
        protocol servers).

     3.4.5.  QUOTED-STRINGS

        Where permitted (i.e., in words in structured fields)  quoted-
        strings  are  treated  as a single symbol.  That is, a quoted-
        string is equivalent to an atom, syntactically.  If a  quoted-
        string  is to be "folded" onto multiple lines, then the syntax
        for folding must be adhered to.  (See the "Lexical Analysis of


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        Messages"  section  on "Folding Long Header Fields" above, and
        the section on "Case  Independence"  below.)   Therefore,  the
        official  semantics  do  not  "see" any bare CRLFs that are in
        quoted-strings; however particular parsing programs  may  wish
        to  note  their presence.  For such programs, it would be rea-
        sonable to interpret a "CRLF LWSP-char" as being a CRLF  which
        is  part  of the quoted-string; i.e., the CRLF is kept and the
        LWSP-char is discarded.  Quoted CRLFs (i.e., a backslash  fol-
        lowed  by  a CR followed by a LF) are also subject to rules of
        folding, but the presence of the quoting character (backslash)
        explicitly  indicates  that  the  CRLF  is  data to the quoted
        string.  Stripping off the first following LWSP-char  is  also
        appropriate when parsing quoted CRLFs.

     3.4.6.  BRACKETING CHARACTERS

        There is one type of bracket which must occur in matched pairs
        and may have pairs nested within each other:

            o   Parentheses ("(" and ")") are used  to  indicate  com-
                ments.

        There are three types of brackets which must occur in  matched
        pairs, and which may NOT be nested:

            o   Colon/semi-colon (":" and ";") are   used  in  address
                specifications  to  indicate that the included list of
                addresses are to be treated as a group.

            o   Angle brackets ("<" and ">")  are  generally  used  to
                indicate  the  presence of a one machine-usable refer-
                ence (e.g., delimiting mailboxes), possibly  including
                source-routing to the machine.

            o   Square brackets ("[" and "]") are used to indicate the
                presence  of  a  domain-literal, which the appropriate
                name-domain  is  to  use  directly,  bypassing  normal
                name-resolution mechanisms.

     3.4.7.  CASE INDEPENDENCE

        Except as noted, alphabetic strings may be represented in  any
        combination of upper and lower case.  The only syntactic units








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        which requires preservation of case information are:

                    -  text
                    -  qtext
                    -  dtext
                    -  ctext
                    -  quoted-pair
                    -  local-part, except "Postmaster"