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From Jeremias Maerki <...@jeremias-maerki.ch>
Subject Re: PDF/A validation
Date Wed, 27 Oct 2010 15:57:30 GMT
Thank you for the link, Wim! That is very useful.

I'll look into these issues. Below I'll list my comments to the
individual findings...

On 27.10.2010 13:40:03 Wim VN wrote:
> http://www.validatepdfa.com/ http://www.validatepdfa.com/ 
> The above website allows you to send in pdf files (attached to an e-mail),
> returning you a - rather detailed - report about the pdf/A conformity. In my
> experience the report could easily inform you of errors and inform you of
> not passing the conformity tests, while opening the same pdf file in Acrobat
> Reader indicates the file is PDF/A conform.
> I thought this could help out FOP users who wish to create PDF/A but don't
> have the means of testing the conformity. I know it's been helpful in my
> recent project and I saw some posts in the last few weeks about it.
> It might even be helpfull to the Apache FOP developers. Though Acrobat
> Reader indicated a file I created with FOP 1.0 as being conform, the
> validation service still mentioned failure and following issues:
>   problem severity="warning" objectID="8" clause="p32" standard="xmp">XMP
> packet read-only

I have not found anything in the XMP, PDF 1.4 or PDF/A-1 specs that
indicates that the XMP packet may not be read-only. Of course, using
writable XMP packet opens up additional flexibility. PDF allows
incremental changes to a document thus providing the ability to override
the metadata. A writable packet increases PDF file size by 2-4KB just
for the possibility that a non-PDF-specific tool wants to update the XMP
packet. I know of no such commonly used tool.

>   problem severity="warning" objectID="8" clause="p33"
> standard="xmp">Recommended padding is not found in the XMP packet trailer

Same as above (a writable packet implies the padding). I have not found
any recommendation in XMP, PDF 1.4 or PDF/A-1 about this. As mentioned
above, the recommended padding is 2-4KB which is rather large especially
for smaller files. Maybe this could be made configurable if someone
really wants the padding.

>   problem severity="error" objectID="8" clause="6.7"
> standard="pdfa">Property 'dc:date' used incorrect value type 'simple'
> instead of 'rdf:Seq'

See https://issues.apache.org/bugzilla/show_bug.cgi?id=49499
ISO 19005:1:2005(E) (PDF-A/1) references the XMP specification from
January 2004 which does not explicitely require values to be in the
exact form that they are specified in the schema. There are various ways
a value can be represented in RDF/XML. Currently, XML Graphics Commons
does not normalize values. Only the XMP spec from 2008 seems to have
some comment concerning this, although I can't find the reference
anymore. But maybe this actually refers to clause "6.7.7 Normalization"
in PDF/A-1 although the text is a bit cryptic.

Anyway, it should be relatively simple to add the normalization. But I
make no promises when (and if) I get to this.

>   problem severity="warning" objectID="8" clause="TN0001"
> standard="pdfa">Recommended property 'format' for schema 'dc' missing

That is easily added, but again, I found no requirement anywhere that
mentions this. I guess that's the reason why these are warnings and no

> Possibly other validators like preflight and pdf/a manager will also stumble
> over these issues, while Acrobat Reader is less strict.
> I hope this helps some people in their projects.
> Regards
> Wim
> -- 
> View this message in context: http://old.nabble.com/PDF-A-validation-tp30066770p30066770.html
> Sent from the FOP - Users mailing list archive at Nabble.com.

Jeremias Maerki

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