For some fields, such as "Subject" and "Comments",  no  struc-
        turing  is assumed, and they are treated simply as s, as
        in the message body.  Rules of folding apply to these  fields,
        so  that  such  field  bodies  which occupy several lines must
        therefore have the second and successive lines indented by  at
        least one LWSP-char.

     3.1.4.  STRUCTURED FIELD BODIES

        To aid in the creation and reading of structured  fields,  the
        free  insertion   of linear-white-space (which permits folding
        by inclusion of CRLFs)  is  allowed  between  lexical  tokens.
        Rather  than  obscuring  the  syntax  specifications for these
        structured fields with explicit syntax for this  linear-white-
        space, the existence of another "lexical" analyzer is assumed.
        This analyzer does not apply  for  unstructured  field  bodies
        that  are  simply  strings  of  text, as described above.  The
        analyzer provides  an  interpretation  of  the  unfolded  text


     August 13, 1982               - 6 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


        composing  the body of the field as a sequence of lexical sym-
        bols.

        These symbols are:

                     -  individual special characters
                     -  quoted-strings
                     -  domain-literals
                     -  comments
                     -  atoms

        The first four of these symbols  are  self-delimiting.   Atoms
        are not; they are delimited by the self-delimiting symbols and
        by  linear-white-space.   For  the  purposes  of  regenerating
        sequences  of  atoms  and quoted-strings, exactly one SPACE is
        assumed to exist, and should be used, between them.  (Also, in
        the "Clarifications" section on "White Space", below, note the
        rules about treatment of multiple contiguous LWSP-chars.)

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

            ":sysmail"@  Some-Group. Some-Org,
            Muhammed.(I am  the greatest) Ali @(the)Vegas.WBA




























     August 13, 1982               - 7 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


        is analyzed into the following lexical symbols and types:

                    :sysmail              quoted string
                    @                     special
                    Some-Group            atom
                    .                     special
                    Some-Org              atom
                    ,                     special
                    Muhammed              atom
                    .                     special
                    (I am  the greatest)  comment
                    Ali                   atom
                    @                     atom
                    (the)                 comment