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Re: Series of PDF/UA video tutorials

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From: Olaf Drümmer
Date: Mar 21, 2016 3:58PM

Hi Kelly,

> On 21.03.2016, at 20:49, Kelly Lupo < <EMAIL REMOVED> > wrote:
>
> - I might also suggest explaining why you did *not* choose to check
> "Create PDF/A-1a:2005 compliant file." I was curious myself as to why you
> did not, so I imagine other beginner "newbs" may be as well. :)

one main reason is that PDF/A-1 disallows the use of ‘transparency'. If transparent objects (think 'text highlighted in yellow' or ‘drop shadow effect' etc.) are present in a Microsoft Office these objects (and those that overlap with these transparent objects) will have to be replaced by one or more objets that do not use transparency but still look the same. In numerous cases this could mean that text or vector objects are rasterized - which then makes it impossible to tag these properly.

Another important reason is that PDF/A-1 limits the number of tag objects you can have to 8191. This may sound like a lot but will easily be exceeded in longer documents.

PDF/A-1 had been released in 2005 and was based on PDF 1.4. In the meantime, PDF/A-2 - which does allow transparency, does not have a limit of 8191 tag objects, and is based on PDF 1.7 per ISO 32000-1 - has been released (in 2011) and is recommended over PDF?A-1 for all digital born documents (as opposed to for example scanned documents where PDF/A-1 can still be quite OK though PDF/A-2 can be used as well for these). Unfortunately Microsoft did not find the time so far to also implement support for PDF/A-2.


For those not familiar with the PDF/A family of ISO standards - they have been invented to support long term preservation of electronic documents and are widely used in archiving.


Olaf