These are the v1 data files for Matbench Discovery, a benchmark for machine learning energy models on inorganic crystal stability prediction from unrelaxed structures. It contains relaxed structures of the MP training set, initial+relaxed structures of the WBM test set, plus several checkpoints for models trained on this data specifically for this benchmark.
For a description of each file, see https://matbench-discovery.materialsproject.org/contribute#--direct-download.