We are providing PDFA1B compliant PDFs for those clients that care to have it. 

This is an standard for PDFs that are to be archived for potential future use.

The standard requires things like downloading fonts, making sure the PDF does not have external dependencies, that the content is not password protected, that colors and images meet certain requirements, types of stuff the should help make the PDF usable by future visiting aliens, whom, after they attempt to read it, will likely go home.

We check that these PDFs are compliant using Adobe preflight and Datalogics Normlizer software.  These applications pass the our PDFs as being OK compliant. 

A third check, however (and from a webbbb site), is flunking the PDF, with the following error message: 

   The dictionary must not contain the key 'Filter'.

How cryptic is that! 

Anyway, for the sake of due diligence, if anyone can help translate the message into human form, we'd appreciate your transmission.

Regards,

John Hoffman