Even though the related specs are not part of the actual W3C HTML5 spec, they are considered by many people to be HTML5 in the broader sense.
That being said, many of those related specs were part of HTML 5 in the past, but spun of to there own spec. Others were proposed on the WhatWG working group, part of the WhatWG Living HTML spec or extensions to HTML 5 elements.
That being said, many of those related specs were part of HTML 5 in the past, but spun of to there own spec. Others were proposed on the WhatWG working group, part of the WhatWG Living HTML spec or extensions to HTML 5 elements.