The PDF/A Extension enables the conversion of arbitrary PDF files to PDF/A 1b, 2b, 3b and into the ZUGFeRD format (ZUGFeRD is a German invoice format that based on PDF/A 3). Besides classical PDF/A conversion PDF files can also be normalized and optimized. The PDF/A Extension allows unlimited use of the functions CheckConformance(), Optimize() and the corresponding helper functions.
PDF/A 1b based on PDF 1.4 and is therefore limited in terms of allowable content because important features such as layers and transparency are not allowed. Layers can be flattened but this is not possible with transparent objects. Such pages could still be converted to an image, but much more convenient would be the output of PDF/A 2 or 3 since these formats support transparency.
PDF/A 2b and PDF/A 3b
Because layers and transparency are allowed in PDF/A 2 and 3, most PDF files can be easily converted into these formats. PDF/A 2 and 3 are almost identically, the only difference is that file attachments are allowed in PDF/A 3. The restrictions for interactive objects are comparable with PDF/A 1 but many more annotation types are allowed.
PDF/A files are fully rebuild and optimized during conversion. Useless operators or errors in content streams are removed too. The resulting files are smaller and can be rendered or printed faster. How much the optimization takes effect depends on the quality of the source material.
In addition to PDF/A 3 also ZUGFeRD compliant invoices can be generated. The ZUGFeRD format simplifies and standardize the exchange of invoices between companies and authorities.
A ZUGFeRD invoice consists of a PDF/A 3 compliant PDF file and an XML version of the invoice that is attached to the PDF file. The PDF file represents the visual presentation while the XML file is intended for electronic processing. The XML and PDF file have a well defined structure, therefore, an electronic processing is very easy.
The PDF/A Extension is not required to create new ZUGFeRD compliant PDF files. It is only required if the PDF file contains imported pages whose conformance to PDF/A 3 is unknown.
DynaPDF is no XML library. Therefore, the creation of the XML invoice is not part of DynaPDF. However, the XML invoice can be attached to the PDF file with DynaPDF.
During normalization a PDF file should be prepared in a manner that it can be printed without problems, also if the source file contains errors. Files with critical errors should be identified and sorted out. This avoids unnecessary waiting times, especially in the mass printing.
Normalization is comparable with PDF/A conversion. The file will be completely rebuilt and non-embedded fonts can be embedded or left unchanged. Layers and form fields can be flattened too if necessary.