Right now, ApplyStyleCommand is responsible for both determining which style, elements, attributes to be removed and to be added. In the long run, we'd like to move this responsibility over to EditingStyle. This is bug is about moving HTMLEquivalent and its subclasses along with the logic to determine which elements and attributes are moved from ApplyStyleCommand to EditingStyle. While this introduces a slight overhad, it simplifies the code in ApplyStyleCommand significantly and helps to separate the responsibilities of ApplyStyleCommand and EditingStyle so it should be a win in the long term.