Again, popularly, an unproved ex cathedra statement of any kind is called " dogmatic," with perhaps an insinuation that it is being obstinately adhered to without, or beyond, or in defiance of, obtainable evidence.
The Apostolic Letters alone may be ex cathedra documents, and may have the privilege of infallibility, if the matter admit of it.
The statement in one of his works that the pope could err in matters of faith ("haeresim per suam determinationem aut Decretalem asserendo") has attracted attention; but as it is a private opinion, not an ex cathedra pronouncement, it is held not to prejudice the dogma of papal infallibility.
To issue an infallible statement " you make a dogmatic statement ' ex cathedra ' from the chair of Peter " .
His pronouncements are held to be infallible when he defines a doctrine concerning faith or morals ex cathedra to be held by the universal church (see Infallibility and Vatican Council).