I found a PDF with a book (or articles) about this issue, by Frantisek Kubat.
There is a table with the perforation known to the issue.http://www.csphilately.net/wp-conte...8/hrad03.pdf
(last 2 pages)
Is this table quite a good match to the table in POFIS? Or is it a bit outdated (although from 2006)?