ual to 0 for a coded IDR bottom field. Thus, at least one of TopFieldOrderCnt and BottomFieldOrderCnt shall be equal to 0 for the fields of a coded IDR frame. When the current picture is not an IDR picture, the following applies: 1) Consider the list variable listD containing as elements the TopFieldOrderCnt and BottomFieldOrderCnt values associated with the list of pictures including all of the following: a. The first picture in the list is the previous picture of any of the following types: an IDR picture, a picture containing a mnemory_management_control_operation equal to 5. The following additional pictures: If pic_order_cnt_type is equal to 0, all other pictures that follow in decoding order after the first picture in the list and are not "non-existing" frames inferred by the decoding process for gaps frame num specified in clause 8.2.5.2 and either precede the current picture in decoding order or are the current picture. When pic_order_cnt_type is equal to 0 and the current picture is not a "non-existing" frame inferred by the decoding process for gaps in frame num specified in clause 8.2.5.2, the current picture is included in listD prior to the invoking of the decoded reference picture marking process. Otherwise (pic_order_cnt_type is not equal to 0), all other pictures that follow in decoding order after the first picture in the list and either precede the current picture in decoding order or are the current Rec. ITU-T H.264 (01/2012) picture. When pic_order_cnt_type is not equal to 0, the current picture is included in listD prior to the invoking of the decoded reference picture marking process. Consider the list variable listO which contains the elements of listD sorted in ascending order. listO shall not contain any of the following: a pair of TopFieldOrderCnt and BottomFieldOrderCnt for a frame or complementary field pair that are not at consecutive positions in listO, a TopFieldOrderCnt that has a value equal to another TopFieldOrderCnt, a BottomFieldOrderCnt that has a value equal to another Botto