RadPdfProcessing currently supports interactive forms whose data is defined directly in the document. To preserve them when importing and exporting documents, add support for import-export interactive forms based on the Adobe XML Forms Architecture (XFA).

From PDF 2.0 the XFA forms are depreciated.

Following the steps:

1. Create two PDF documents that contain form fields where the name contain a period, e.g. "person1.name".

2. Merge the two documents:  https://docs.telerik.com/devtools/document-processing/libraries/radpdfprocessing/model/interactive-forms/form-fields/formfields#merging-documents-with-form-fields 

PdfStreamWriter: "InvalidOperationException: 'isContentReleased'" is thrown when creating a multi-page document with an umlaut on the last page.

block.TextProperties.Font = FontsRepository.Courier;

Support for FileAttachment annotations. 

A file attachment annotation contains a reference to a file, which typically is embedded in the PDF file.

SkiaImageFormatProvider: Add support for Text, TextMarkup, Line, and Stamp annotations.

Currently, these annotations are omitted on image export.