HTML Purifier 2.0 is the culmination of two major architectural changes. 
The first is Tidy, which enables HTML Purifier to both natively support 
deprecated elements and also convert them to standards-compliant 
alternatives. The second is the Advanced API, which enables users to 
create new elements and attributes with ease. Keeping in line with a 
commitment to high quality, there are also five esoteric bug-fixes and a 
plethora of subtle improvements that enhance the library.