[pdftex] Description of the /AF key

[Ross Moore]

Hi Reinhard,

You are correct in that an embedded file (usually as an attachment) need not be the same as an /AF associated file. 

Associated files are meant to be treated as a *replacement* for the content associated with a structural element, such as a Figure or Formula.
For such a replacement to be used, the PDF consumer software needs to be able to call on (perhaps external application) software to interpret the contents of that file. Normally there will be a rectangle in which to show the graphic result from that software.

An Embedded file, on the other hand, does not contribute to the way the view of the PDF’s content is displayed, apart from having an annotation that indicates its presence, and links to a way to extract the file for external use. 
This is just like having an attachment to an email message.

The AssociatedFile structure is more involved than an EmbeddedFile, which latter has been around in the PDF standards for much longer.


Hope this helps.

     Ross

Sent from my iPhone

> On 24 Aug 2023, at 7:12 pm, Reinhard Kotucha <reinhard.kotucha at gmx.de> wrote:
> 
> On 2023-08-23 at 21:20:25 +0000, Ross Moore wrote:
> 
>> If I recall correctly, /AF was introduced with PDF/A-3, which has
>> its own ISO document, some years after ISO 32000.
> 
> Thank you very much Ross and Karl,
> so it seems that /AF was added to embedfile.sty to support PDF/A.
> This means that that can't rely on it when trying to extract embedded
> files from PDF files created by other programs than *tex.  This is why
> I asked.
> 
>> It is in PDF 2.0.
>> There is now free documentation for this via the PDF Association.
> 
> I've downloaded it a few weeks ago but didn't expect to find a
> description there because pdftex and embedfile.sty are much older than
> PDF 2.
> 
> Thanks,
>  Reinhard
> 
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