The PDF visualizer http://issuu.com/ISSUU is a popular service allowing to show PDF documents “a page a time”. Due to the way it is implemented, internal links in these documents are not allowed. Instead, they must be converted to external ones in the form http://issuu.com/action/page?page=PAGENUMBER. The package patches hyperref to produce external links in the required form instead of internal links created by \ref, \cite and other commands. Since the package redefines the internals of hyperref, it must be loaded it AFTER hyperref.