IPP Mail Archive: RE: IPP> Media Standardized Names - Units

IPP Mail Archive: RE: IPP> Media Standardized Names - Units

RE: IPP> Media Standardized Names - Units

From: Hastings, Tom N (hastings@cp10.es.xerox.com)
Date: Thu Apr 19 2001 - 21:41:25 EDT

  • Next message: Hastings, Tom N: "RE: IPP> I-D ACTION:draft-ietf-ipp-notify-get-03.txt [companion f ormats down-loaded]"

    We need to understand better where conversion from inches to mm or vice
    versa might occur.

    As I said in a previous mail message, the Media Size Self Describing Name is
    really a keyword, not a name and not a set of attribute values.

    I don't think that we expect that the Media Size Self Describing Name tokens
    would be send from client to printer or printer to client using either form
    of units for a given size. In other words, we don't expect that a Printer
    would support both:


    So only the first value is needed for interoperability between client and

    We probably need to add a note about *not* having both forms for the same
    size (either in the standard or in actual interchange), judging from the
    confusing that this email discussion is showing.

    Instead, these tokens are really keywords and the proper units are sent for
    the size, even if the user is running in the opposite locale. Sure a good
    client will be displaying the sizes to the user in the units that the user
    has set for his locale (inches or mm). But we don't want to double the
    number of tokens, by having both an English version and a metric version.

    Mark indicates that the Driver (or Printer) might keep all dimensions
    internally in only one set of units. That is a good implementation
    technique (but outside the scope of our Media standard). I'd suggest that
    for such an internal implementation is where 100th of mm is a good bet, to
    avoid the round off problem. But our Media Standardized Names is NOT
    specifying how client and printers represent things internally, but how they
    interchange between each other. (Similarly, our standard is also *not*
    specifing how a client displays our names to the user).

    I'm not sure we even have a problem for custom sizes, though it isn't so
    Two cases:

    a. The Administrator defines the custom sizes that his shop/printer has.
    b. The user defines the custom sizes that he/she wants, whether or not the
    shop/printer has them.

    In the a case, the Administrator would use the units that his users were
    most likely know. He might have to define the same custom size in both sets
    of units, if he was in a local that had both English and Metric users. But
    that's a conversion he does when he defines the sizes, its not an algorithm
    performed by some software.

    In the b case, the European user would want to specify the custom size in mm
    (and the client converts to 1/10 mm before sending to the Printer), while
    the North American would want to specify the custom size in inches (and the
    client converts to 1/1000 inches before sending to the Printer).

    Again, there doesn't seem to be the need for more precision in the mm case;
    1/10 mm seems sufficient.



    -----Original Message-----
    From: Hastings, Tom N [mailto:hastings@cp10.es.xerox.com]
    Sent: Thursday, April 19, 2001 17:01
    To: ipp (E-mail)
    Subject: FW: IPP> Media Standardized Names - Units

    This mail note brings up the conversion issue of the client converting the
    media units from one to the other in order to display the units in the
    locale of the user.

    It was not forwarded to the IPP list.


    -----Original Message-----
    From: Mark Hamzy [mailto:hamzy@us.ibm.com]
    Sent: Thursday, April 19, 2001 07:18
    To: Mark VanderWiele; hastings@cp10.es.xerox.com; Harry Lewis; Pete
    Subject: RE: IPP> Media Standardized Names - Units

    Here are two examples. There are around 10 or so that I found.

    There is a need to convert from one to another. One case would be that a
    driver keeps one units of measurement internally and converts as needed
    externally. User interfaces should have the ability to let the user decide
    what units of measurement to display in, so you would need to give a letter
    form in metric measurement.
    I think that both could be acceptable as input. For the metric user,
    letter would look like letter.2159-2794. I think that the na- prefix is
    akward. It would be better to place it in front of the dimension. Also,
    it would allow other units of measurement to be used (twips for example).




                        VanderWiele To: Mark
    Hamzy/Austin/IBM@IBMUS, Pete
                        04/18/01 06:28 cc:

                        PM From: Mark
                                             Subject: RE: IPP> Media
    Standardized Names -




    Mark VanderWiele
    IBM, Linux Technology Center
    512-838-4779, t/l 678
    email: markv@us.ibm.com
    ---------------------- Forwarded by Mark VanderWiele/Austin/IBM on
    04/18/2001 06:28 PM ---------------------------

    04/18/2001 04:05 PM

    To: Mark VanderWiele/Austin/IBM@IBMUS
    From: Harry Lewis/Boulder/IBM@IBMUS
    Subject: RE: IPP> Media Standardized Names - Units

    Mark, I forget who it was in your office who brought this up. Do they care
    to address this?
    Harry Lewis
    IBM Printing Systems
    ----- Forwarded by Harry Lewis/Boulder/IBM on 04/18/2001 03:02 PM -----

                        "Hastings, Tom N"

                        <hastings@cp10.es. To: Harry Lewis
                        xerox.com> RonBergman@aol.com

                        Sent by: cc: ipp@pwg.org

                        owner-ipp@pwg.org Subject: RE: IPP> Media
    Standardized Names -


                        04/17/2001 06:02





    There are exactly 254 mm in an inch, so the precision is about the same,
    inches are about 4 times more precise than the metric units.

    For example, the two most popular Self Describing Size Names are:

    The letter size (8.5 inches by 11 inches) used in North America:
    The iso A4 size (210 mm by 297 mm) used in metric countries:

    Note that they both have about the same number of digits in each dimension,
    namely around 4.

    Also there isn't any need to convert from inches to mm or vice versa,
    because the paper size is given ONLY in the natural units for the usage.
    North American sizes only use 1000ths of inches and aren't converted to mm.
    Similarly, the non-English sizes are always given in 10ths of mm and aren't
    converted to inches. Therefore, there is never any rounding errors to

    The only rounding that could occur, is if some paper size is actually in
    some fraction of inches, or mm, such as 200 1/3 mm or 10 1/3 inches. But I
    don't think we have any sizes like that.



    -----Original Message-----
    From: Harry Lewis [mailto:harryl@us.ibm.com]
    Sent: Monday, April 16, 2001 15:33
    To: RonBergman@aol.com
    Cc: ipp@pwg.org
    Subject: IPP> Media Standardized Names - Units

    I'm questioning the use of 1/1000 for English but only 1/10 for metric.
    Not only are we loosing precision, but, also introducing rounding errors
    during conversion from English to metric . I know the printer MIB heritage
    is 1/1000 English and 1/10 metric... but
    I think we should try to be more precise in this new media mapping.
    Harry Lewis
    IBM Printing Systems

    Sent by: owner-ipp@pwg.org
    04/09/2001 02:26 PM

            To: <ipp@pwg.org>, <upd@pwg.org>
            Subject: IPP> Fwd: FW: Media Standardized Names, Version
    is now available

    ----- Message from "Bergman, Ron" <Ron.Bergman@Hitachi-hkis.com> on Mon, 9
    Apr 2001 08:02:14 -0700 -----
    "'RonBergman@aol.com'" <RonBergman@aol.com>
    FW: Media Standardized Names, Version D0.6 is now available

    -----Original Message-----
    From: Bergman, Ron [mailto:Ron.Bergman@HITACHI-HKIS.COM]
    Sent: Monday, April 09, 2001 8:01 AM
    Subject: Media Standardized Names, Version D0.6 is now available


    The latest draft is now available at:

            ftp://ftp.pwg.org/pub/pwg/media-sizes/pwg-media-06.pdf (or .doc)

    I will not repeat the abstract here or the list of changes. This
    information is
    available within the document, if you are interested. The major change to
    version is the addition of the "Media Finish Names".

    This document will have a final review in the PWG meetings during the week
    of April 23rd and should then be ready for last call.

            Ron Bergman
            Hitachi Koki Imaging Solutions

    This archive was generated by hypermail 2b29 : Thu Apr 19 2001 - 21:42:55 EDT