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What are the benefits and risks of using the PDF-A file format?

+5 votes
1,061 views
asked Mar 7, 2014 by JMandelbaum (290 points)

1 Answer

+4 votes
Starting from the assumption that you are already dealing with PDFs as the incoming format, PDF/A has a number of advantages, especially in terms of encapsulation. A properly created PDF/A will ensure that there are no dependencies on external resources by embedding them inside the file. This is particularly important for fonts, but also applies to other media and content. Similarly, a well made PDF/A should also meet a certain standard in terms of embedded metadata.
 
The downside is that if your original document contains any of the things that PDF/A disallows (various embeds like 3D, JavaScript and so forth) they will, at best, be replaced with static versions and at worst, silently discarded. Given that the imminent obsolescence of these features is highly debatable, it's not necessarily clear that this is a sensible step. Certainly, discarding the original and keeping only the PDF/A may be a very bad idea (depending on the context).
 
PDF/A-3 represents a kind of middle-ground hack here, by allowing arbitrary resources to be packaged alongside the document. This NDSA report gives a excellent overview of the issues. My personal opinion is that, at present, the PDF/A-3 cure is worse than the obsolescence disease, and I would prefer a flavour of PDF that enforces embedded fonts etc. but discards nothing.
 
When the incoming format is not already PDF the situation is similar to the above, but much more extreme. It's even harder to know whether what you are throwing away is important, and so keeping the original becomes even more necessary. For example, conversion to PDF/A does not necessarily imply that the external dependent resources of the original item will be picked up correctly. Finally, a decision to normalise multiple formats to PDF implies a lot of assumptions about modes of future discovery and use of the material, and I'm not convinced those assumptions will stand the test of time.
answered Mar 8, 2014 by anjackson (2,930 points)
To me, the most dangerous aspect of normalizing to PDF is that it commits the information to an 8.5x11, A4, or other paper-based format. This might not be the standard in the future as it is today.
Correct me if I am wrong, but the PDF/A standard doesn't require a page size. Committing to an 8.5x11 or other paper size if purely if you use a print-to-pdf where it uses a print driver. I have created quite a few PDF/A's that are cropped to the intended size. As long as the PDF is sized the same as the original document, I don't see it as much of an issue.
@Thorsted

Apparently there are some constraints on page size. See:

<https://web.archive.org/web/20140822223704/http://www.pdfa.org/2013/02/pdfa-facts/>

Which says:
 
> PDF/A also sets technical limits: for example, the page size is limited to an edge length of either 5.08 metres (PDF/A-1) or up to 381 kilometres (PDF/A-2 and PDF/A-3).

Probably irrelevant for most practical purposes, but there may be extreme cases ....
Johan just published a great article on this here: http://www.openplanetsfoundation.org/blogs/2014-08-27-when-not-migrate-pdf-pdfa
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