(ii) Inclusion of certain entities Such term may include an entity engaging in activities that the Secretary has determined constitute significant progress toward establishing a model referred to in any of subclauses (I) through (IV). Any waiver under this paragraph with respect to an entity described in the preceding sentence may only be approved for three years. (C) Certain requirements A model referred to in any of subclauses (I) through (IV) of subparagraph (B)(i) may not be considered a covered APM entity for purposes of subparagraph (A) unless the model meets the requirements described in section 1877(b)(6)(B).