(1) assign default parameter values to root (tt) binding content object if not specified;
(2) assign default (initial) style values to root (tt) binding content object if not specified;
(3) add verification parameter sets;
(4) ensure dur(ation) is invalid when specified with smpte - discontinuous mode;
(5) add test to verify dur(ation) is invalid when specified with smpte - discontinuous mode;