XP Mail Archive: RE: XP> xhtml-print: RFC3391 interpretation

RE: XP> xhtml-print: RFC3391 interpretation question: how much vi sual sep aration ends a chunk?

From: PARAB,DEEPALI (HP-Boise,ex1) (deepali.parab@hp.com)
Date: Thu Apr 08 2004 - 12:24:31 EDT

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    Hi Jim,
    My experience says that its should be,
    ==================================
    </body>
    </html>
    CHK 0 0 LAST
    ==================================
    The reason is,
    carriage return (ASCII code 0Dh), which positions the cursor to the left
    side of the current line of characters,
    line feed (ASCII code 0Ah), which moves the cursor down one line on the
    output device.
    So if the code is as follows
    ===========================
    A)
    </html><CR><LF>CHK 0 0 LAST then we should get
    OR
    </html><LF>CHK 0 0 LAST
    Then the output would be,
    </body>
    </html>
    CHK 0 0 LAST
    ===========================
    B) But if an additional <LF> (<0a>) is inserted like shown,
    </html><CR><LF><LF>CHK 0 0 LAST
    OR
    </html><LF><LF>CHK 0 0 LAST

    Then the output would be,
    </body>
    </html>

    CHK 0 0 LAST
    ==========================
    I have observed that PDF file formats (I have worked on then till 1.4
    Version) also have this interpretation of CR/LF. Note that this was seen on
    windows environment.

    Regards,
    -Deepali

    -----Original Message-----
    From: owner-xp@pwg.org [mailto:owner-xp@pwg.org] On Behalf Of BIGELOW,JIM
    (HP-Boise,ex1)
    Sent: Thursday, April 08, 2004 9:52 AM
    To: www-html-editor@w3.org; Elliott Bradshaw; don@lexmark.com
    Cc: xp@pwg.org
    Subject: XP> xhtml-print: RFC3391 interpretation question: how much visual
    sep aration ends a chunk?

    I'm looking for opinions on the interpretation of RFC3391 [1] since it is
    normatively referenced by XHTML-Print [2].

    RFC 3391 says,
       An Application/Vnd.pwg-multiplexed entity contains a sequence of
       chunks. Each chunk consists of a chunk header, a chunk payload and a
       CRLF.

         - The chunk header consists of a "CHK" keyword followed by the
           message number, the chunk payload length, whether the chunk is
           the last chunk of a message and, finally, a CRLF. The length
           field removes the need for boundary strings that Multipart uses.
           (See section 3.1 for the syntax of a chunk header).

         - The chunk payload is a sequence of octets that is either a
           complete message or a part of a message.

         - The CRLF provides visual separation from the following chunk.

    There are several situations where a single CRLF does not provide visual
    separation since the CRLF added to the document simply terminates a line
    rather than adding a empty line. For example in an XHTML-Print document
    didn't contain a terminating CRLF and adding a single CRLF would give the
    result shown below in example 1:

    </body>
    </html>
    CHK 0 0 LAST

    Rather than the following, example 2, I expected from reading the spec:

    </body>
    </html>

    CHK 0 0 LAST
       
    This could also occur when interleaving images and the root document.

    I think this issue will have a large impact on interoperability between
    printers and producers of multiplexed documents. So I'd like to get other
    people's interpretations of this matter.

    If I don't hear from anyone, I'll assume agreement that the multiplexed
    document should contain visual separation at the end of the chunk, as in the
    example 2.
     

    Jim

    [1] http://www.ietf.org/rfc/rfc3391.txt
    [2] http://www.w3.org/TR/xhtml-print/



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