Corrections to ISO standards for PDF technology (Errata) are published by the PDF Association as a series of PDF markup annotations in XFDF format that can be applied directly to licensed ISO standards for use with PDF viewers that display PDF annotations.

XFDF is an XML-based file format that is largely equivalent to FDF which can contain PDF form fields and annotations. XFDF is standardized by ISO 19444-1:2019.

Using an interactive PDF viewer

Many interactive PDF viewers can readily import XFDF files, automatically merging the annotations to the PDF, which would then be viewable on an annotation pane or equivalent. On some platforms, the .xfdf file extension may be associated with a PDF viewer allowing users to simply double-click the XFDF file.

The Eratta XFDF files published by the PDF Association do not contain the filename of the associated ISO standard as the filename varies depending on how the standard is acquired. During import, the interactive PDF viewer should prompt for the correct PDF. If not, open the correct ISO standard PDF file and then import the XFDF file.

Once the XFDF is merged, many viewers will allow a new PDF to be saved or exported subject to ISO licensing restrictions.

To validate a successful merge of XFDF into a PDF-based ISO standard, compare the on-screen appearance to the errata at https://pdf-issues.pdfa.org/. If the annotations are misplaced on the page or are occurring on different pages, please see Adjustments to accommodate modified ISO publications below.

The following interactive PDF viewers are known by PDF Association staff to support direct importing of XFDF. Please refer to vendor documentation for more information (alphabetical by vendor):

• Adobe Reader and Acrobat
• Foxit PDF Reader
• Nitro Pro
• Qoppa PDF Studio
• Tracker Software PDF-XChange Editor

NOTE: if you produce a PDF viewer that supports XFDF get in touch to let us know!

Checking XFDF files

In order to confirm that downloaded XFDF files are not corrupted or malformed, the SHA256 hash of an XFDF file can be checked using the command line as follows:

Microsoft Windows:

C:\folder> certUtil -hashfile file.xfdf SHA256

Mac OS and Linux:

/folder$ sha256sum file.xfdf

Applying XFDF from the command line

iText has developed XFDF-merger (GitHub link), a free command-line tool, which can merge an Errata XFDF with a PDF to create a new PDF that includes all the XFDF content. This output PDF supports PDF viewers that cannot import XFDF, but will display PDF annotations.

The following example uses the iText XFDF-merger command-line utility to apply the Errata XFDF file (iso-32000-2-2020-amd1.xfdf) to ISO 32000-2:2020 (iso-32000-2-2020.pdf). Note that the original ISO 32000-2:2020 PDF is not modified and a new PDF file (iso-32000-2_with_amd1.pdf) is created that includes all the errata corrections:

./xfdfmerge.sh iso-32000-2-2020.pdf iso-32000-2-2020-amd1.xfdf iso-32000-2_with_amd1.pdf

Adjustments to accommodate modified ISO publications

Some national standards bodies and other vendors modify the ISO publication PDF files they sell by inserting additional front matter pages and/or scaling page content to allow for watermarking or altering the page size. Because PDF Association’s Errata XFDF files are based on the official ISO publication, accommodating ISO standards sold by these other vendors require that an Errata XFDF file must be adjusted accordingly.

ISO standards purchased through the PDF Association store do not have this issue.

For example, the British Standards Institute (BSI) sells ISO standards with several modifications: 

National Body	Additional pages	Page offset in points (X)	Page offset in points (Y)	Page scaling factor
BSI	3	+26	-6	94% (0.94)

The following example uses the iText XFDF-merger command-line utility to apply the Errata XFDF file (iso-32000-2-2020-amd1.xfdf) to ISO 32000-2:2020 that was purchased via BSI (bsi-iso-32000-2-2020.pdf). Note that the original BSI file is not modified and a new PDF file (iso-32000-2_with_amd1.pdf) is created:

./xfdfmerge.sh bsi-iso-32000-2-2020.pdf iso-32000-2-2020-amd1.xfdf iso-32000-2_with_amd1.pdf 3/26/-6/0.94

If you find issues with ISO publications from other national standards bodies, please let us know via email info@pdfa.org.