Hi,

sometimes it is important to have the information which special software
created an application. This makes sense if you still have the original
or incoming data.
Consider the following problem: you migrate/process your data with buggy
software what you don't know (a real world exmaple: a broken PDF-lib
under Solaris).
After 5 years you find out, that your data can't be processed in the
expected way. But you still have the original data (which is planned in
the kopal project).
The creating application information is not just information for
decoding and lossy data processing, but also for the curation of your
data and further processing.
Another point are proprietary extensions or just special ways of
interpretations of standards. You might want to be informed about the
tiny differences which may help you to be happy in the future ;-)

Olaf


Zhiwu Xie schrieb:
> Maybe creatingApplications does not have to be directly linked to
> compositionLevel? I think this part of the data dictionary is good as it
> is.
>
> compositionLevel seems to assume you can trace back the original file or
> bitstream by reversing the encoding/bundle, regardless of the
> creatingApplication. You may zip-compress the file with WinZip, but
> without knowing the creatingApplication is Winzip, with only the
> information that the file is zip compresed, we can use other
> applications such as winrar to unzip the file. The encoding information
> is supposed to be clear from the format info, therefore independent from
> the creatingApplication, or at least the creatingApplication should be
> obvious given the format info. Because this is just for
> decoding/unbundling, the date and time info is not important therfore is
> not recorded.
>
> creatingApplication seems to serve some other purposes. If the creating
> process is a lossy one, e.g., apply a lossy compression to a jpeg file,
> or with an application that is close source/propriatery, e.g., create a
> pdf with Acrobat from a MS word file, then we will not be able to get
> back the original word file, even if the creatingApplication is readily
> available. I think this part of info is just for the sake of preserving
> as much as we know about the creating process, just in case they will be
> useful later, but not necessarily readily useful for decoding or
> unbundling.
>
> Although the sequence info for the the creatingApplication is useful,
> (becasue applying application A then B to a file does not necessarily
> get the same result as applying B then A) but such info may be inferred
> from the dateCreatedByApplication. If the later is not avilable, all we
> can say is we don't know much about how the creating was done.
>
> Hope this makes sense,
>
> Zhiwu
>
>
> On the other hand, given multiple creatingApplications
>
> An example would be if I creat a jpeg file by compress the
>


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Olaf Brandt
Project kopal
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