IPP Mail Archive: RE: IPP> MED - Proposed final ABNF for Med

IPP Mail Archive: RE: IPP> MED - Proposed final ABNF for Med

RE: IPP> MED - Proposed final ABNF for Media Size Self Describing Names

From: Hastings, Tom N (hastings@cp10.es.xerox.com)
Date: Mon Jul 09 2001 - 17:46:00 EDT

  • Next message: Bergman, Ron: "RE: IPP> MED - Proposed final ABNF for Media Size Self Describing Names"

    I should have pointed out that the name field will now be required for a
    custom size name, as well as standardized names, whereas in Draft D0.9 the
    name field was optional in custom names.

    There are two advantages to requiring a name field in a custom size name:

    1. The syntax for custom and standard names becomes the same, simplifying
    implementation (since both will require a name).

    2. It is good practice for an administrator when defining a custom size to
    invent some sort of a name to suggest the size's use to its users.

    Ron,

    About your second question, I see I wasn't clear about whether or not the
    ABNF would appear in the standard or only in the PWG FTP site. I think that
    the first ABNF (current with version 1.0 of the standard) should be in the
    standard, including the commenting, so that implementations can see what to
    expect in case they choose to fetch the current (updated) ABNF from the PWG
    site.

    When we post the final approved standard, we should also post the ABNF flat
    file which will be identical to what is in the standard. Only when we
    register a new size name that needs a new class name, will we need to update
    the ABNF flat file on the PWG server. Periodically, but not more frequently
    than, say, once a year, we will update the standard with new size names and
    any new class names that have been registered in the meantime.

    Another reason to include the ABNF in the standard is that fetching the
    current ABNF from the web site isn't required (for an implementation or an
    implementer).

    Tom

    -----Original Message-----
    From: Bergman, Ron [mailto:Ron.Bergman@Hitachi-hkis.com]
    Sent: Monday, July 09, 2001 11:23
    To: 'Hastings, Tom N'; ipp (E-mail)
    Subject: RE: IPP> MED - Proposed final ABNF for Media Size Self
    Describing Names

    Tom,

    It should be pointed out that this does change the current syntax for custom
    size names, in that the "size-name" will be mandatory. This part is
    optional in the current draft.

    Also, I would like a clarification. Does this proposal completely remove
    the size ABNF from the document? Or, is the ABNF included with a note
    indicating where to get the latest? Although it may be somewhat confusing,
    it would be cleaner to only include the reference to the ABNF.

            Ron

    -----Original Message-----
    From: Hastings, Tom N [mailto:hastings@cp10.es.xerox.com]
    Sent: Monday, July 09, 2001 10:57 AM
    To: ipp (E-mail)
    Subject: IPP> MED - Proposed final ABNF for Media Size Self Describing
    Names

    Ron and I want to publish a final version of the Media Standardized Name
    standard for Last Call. There are three standards that require its use, so
    we need to complete the Media standard. One is UPnP Basic Printing
    Template. Another is IPP FAX.

    Please send any comments on this proposed ABNF BEFORE we publish the next
    draft. Silence will be interpreted as agreeing with the ABNF.

    ****************************************************************
    Please send any comments by Tuesday, July 17, 2001.
    ****************************************************************

    There has been the suggestion on the mailing list that the ABNF should be a
    single production, including the custom part and the future registered class
    name part as is common practice.

    We are also agreeing to retain the explicit list of class names in the ABNF.
    When a new size name is registered which needs a new class name, then the
    ABNF will be updated to include the new class name. The updated ABNF will
    be available on the PWG site as a flat text file in a published and stable
    URL.

    Advantages of this approach:

    1. All of the ABNF for the Media Size Self Describing Name is specified as a
    single ABNF production, so that code can be written that will be stable,
    even as new media size names are registered with new class names. This is
    the common practice for other standards that use ABNF.

    2. Which class names go with which units is part of the ABNF, so that it is
    clear that using the wrong set of units with a class name violates the ABNF
    and permits a parser to detect such mal-formed ABNF.

    3. Using a single "custom" class name (rather than one for in and one for
    mm) simplifies the parsing for custom names because the parser needs to look
    for one special prefix ("custom"), as with Media Type and Media Color,
    rather than for, say, "custom-in" and "custom-mm" class names. Since
    administrators are defining the custom sizes, not vendors, whether they
    choose in or mm units will depend on their users.

    Disadvantages of this approach:

    1. When new class names are registered, the existing parsers won't be able
    to validate that the units are correct, unless they access the PWG web site
    for the current ABNF. (The standard will NOT require implementations to
    access the PWG web site to get the current ABNF, nor does it require that
    implementations detect corrupt names that use the wrong units).

    The ABNF flat file will have comments at the beginning to identify the date
    and version of the standard and the date and version of the ABNF. The ABNF
    date and minor version number will be updated every time it is updated. The
    ABNF follows RFC 2234.

    Here is the proposed final ABNF as it will appear in the flat file on the
    PWG site in:
    ftp://ftp.pwg.org/pub/pwg/standards/pwg5101-abnf.txt:

    ; ABNF for the Media Size Self-Describing Name
    ; Part of the IEEE/ISTO 5101.1 Media Standardized Names standard
    ; For use with the IEEE/ISTO 5101.1 Standard Version 1.0, July 9, 2001
    ; ABNF version 1.0, July 9, 2001
    ; This ABNF is updated whenever a new media size class name is registered
    ; according to the procedures of IEEE/ISTO 5101.1.

       media-size-self-describing-name =
          ( class-in "_" size-name "_" short-dim "x" long-dim "in" ) |
          ( class-mm "_" size-name "_" short-dim "x" long-dim "mm" )

       class-in = "na" | "asme" | "oe" | "custom" | reg-class-in-name
       class-mm = "iso" | "jis" | "jpn" | "prc" | "roc" | "om" | "custom" |
                  reg-class-mm-name

       reg-class-in-name = ( lowalpha | digit ) *( lowalpha | digit | "." )
       reg-class-mm-name = ( lowalpha | digit ) *( lowalpha | digit | "." )

       size-name = ( lowalpha | digit ) *( lowalpha | digit | "-" )

       short-dim = dim

       long-dim = dim

       dim = integer-part [fraction-part] | "0" fraction-part

       integer-part = non-zero-digit *digit

       fraction-part = "." *digit non-zero-digit

       lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" |
                  "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" |
                  "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"

       non-zero-digit = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

       digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"



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