[tex-live] PDF/X-1a preflight and xetex/xdvipdfmx

Martin Schröder martin at oneiros.de
Tue Dec 11 20:18:48 CET 2012

2012/12/11  <dgatwood at mac.com>:
> I'm trying to generate PDF/X-1a2001 spec-compliant PDF files with
> xetex/xdvipdfmx (xdvipdfmx-0.7.8 from TeXLive 2012), and I'm running into
> one small bug that I can't find a good way to work around.  The xdvipdfmx
> backend seems to be omitting the /ID field in the PDF trailer.
> For spec conformance, if I understand correctly, this should contain an
> array of two MD5 hashes of the body of the document, not including the
> trailer (presumably both containing the same value, given that it is a newly
> created file).  That said, I'm not sure how important the specific value is,
> so long as it is reasonably unique.

First: This is not a TeXLive issue, but is better discussed at the
XeTeX mailing list.

Second: Your understanding is wrong: The /ID just has to be unique.
The spec says: "The value of this entry shall be an array of two byte
strings. The first byte string shall be a permanent identifier based
on the contents of the file at the time it was originally created and
shall not change when the file is incrementally updated. The second
byte string shall be a changing identifier based on the file’s
contents at the time it was last updated."

And yes, they SHOULD be computed via MD5 etc., but don't HAVE to.
Using e.g. the time of day is perfectly allowed.

   Martin (who wrote the code for /ID for pdfTeX, which is still used
           in LuaTeX)

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