Xournal is a program for creating notes and complete existing PDF files with such. It was written for Linux and other platforms with GTK support. Comparable programs are Jarnal, Gournal and Windows Journal. It has been designed for operation with a stylus or mouse and keyboard.
With Xournal to PDF files with text, add handwritten notes and drawings. To view the PDF files Xournal uses the Poppler library program. The PDF content while unchangeable background images.
The remarks may be subsequently stored separately from the PDF for further processing in native Xournal file format. The PDF file remains unchanged and is still needed for display. Alternatively, all content can be saved to a new PDF file, the existing notes below can not be changed.