PPI::HTML is the successor to the now-redundant PPI::Format::HTML.

While early on it was thought that the same formatting code might be
able to be used for a variety of different types of things (ANSI and
HTML for example) later developments with the here-doc code and the need
for independantly written serializers meant that this idea had to be
discarded.

The new module is much cleaner. Simply create an object with the options
you want, pass PPI::Document objects to the "html" method, and you get
strings of HTML that you can do whatever you want with.