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when a CTM specifies an absolute X,Y position of a PDF, is this the PDF CropBox, TrimBox or MediaBox. TrimBox seems logical but I am not convinced this is what all vendors have implemented. I would like to know if TrimBox is the intent and any knowledge of implementations that do/don't follow the rule.

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    4 answers

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      thanks for the clarification.

      In my scenario there is content as I am an imposition device implementing the end functionality, not a process group in an earlier MIS stage and so TrimCTM has already been dealt with as I am performing the final imposition for a digital printer (and the spec also says ignore TrimCTM when input is to imposition process). As such I believe I am correct to use the PDF trim box for the coordinate origin. I have also spoken to another JDF Imposition generator vendor who interprets the spec this way too, ie. for an imposition engine, position based on Trim Box. 

      I am sure anyone reading this would agree - the spec needs to be improved to make the rules clear without having to wade through Questions/Answers.

      Thx

       

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        See Table 8-142 in 1.5 spec.

        It is a bit ambiguity and not so easy to understand if you are not impose specialist but the section on TrimCTM says it must be used if page is replaced afterwards.

        This also includes the case when no content is provided with the original JDF since the CTM is then not valid since it does not know how the mediabox of the PDF relates to its TrimBox. And CTM places mediabox (but imposition program want to specify the trimbox location),.

        No content provided is not related to mime, it means that there is no URL in the contentobject that points to content. So content is provided later manually by prepress operator. Then the PDF Trimbox must be placed using the TrimCTM.

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          I appreciate the answer and your help, but are you describing what happens in an implementation or what you can see in the spec (I cant see any of this detail in the spec although would be grateful if you could point me to some documentation)?

          Could you also clarify what you mean about "content provided", are you referring to the difference between a JMF/JDF where a URL contains a CID reference to a PDF file which is provided in the same multipart mime packet, and a JDF where the URL contains a file or http reference, or something else?

          What would be the perceived reason behind interpreting differently - the PDF spec seems to state it should be TrimBox.

           

          Thanks again.

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            I only know about CTM for the Layout resource (mainly used for conventional printing so probably no good answer). There it is complex since different CTM apply different boxes depending if the content was also delivered at the same time or not.

            If Content is provided, @CTM places the PDF MediaBox.

            If no content is delivered with/ the JDF, or for page updates then @TrimCTM is used to place the PDF TrimBox

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