Originally Posted by janek
If Adobe Acrobat opens it, it is either valid PDF or a miracle.
Like web browsers, I expect PDF-readers to be quite flexible and accept many invalid files.
There is no miracle involved in the acceptance of invalid documents - it is pragmatism. Which invalid HTML files browsers accept varies and that is probably true of PDF readers as well. That is why it might be valuable to examine the PDF file from the perspective of the standard.
Given a valid PDF file, however, I would be quite surprised if it did not display at all in Acrobat (though there are many examples of this as well - just look at the number of patches and revisions there are of the Adobe Reader to prevent carefully crafted PDFs from compromising the OS).