I am frequently called on to proof read entire magazines prior to their being forwarded to the printer. These magazines come to me as PDF documents, so, before discovering Infix, I had to read each PDF page, record my corrections in a text file (e.g. MS Word), and then send the text file back to the writers. This often led to errors in transcribing.
Now, I can make the changes/corrections directly in the PDF and send it back, ready to go. A time saver, and far less chance of human error.
A great little program.