We obtain A2Dre by selecting only instances that were labeled as non-trivial, which are 433 REs from 190 videos. We do not use the trivial cases as the analysis of such examples is not relevant, as referents can be described by using the category alone. Each annotator was presented with a RE, a video in which the target object was marked by a bounding box, and a set of questions paraphrasing our categories. A2Dre was annotated by 3 authors of the paper. Our final set of category annotations used for analysis was derived by means of majority voting: for each nontrivial RE, we kept all category labels which were assigned to the RE by at least two annotators.