It appears that you are referring us to a non-existent 'dogmatic declararion."  You may have been fishing for Vatican One's Pastor Aeternus, sometimes known as the "infallibility decree," which Vatican III would be quite capable and authorized to reform.  As you may already be aware, several voting bishops at Vatican One voted "non placet"  (= NO) to that decree, as it incorporated a whole lot more than "traditional doctrine."  Pastor Aeternus itself thus was an expression of the church;s "ever evolving magisterium."  Puts a whole new light on modernism, huh!