Binary format HDF5 HDF5 is a data model, library, and file format for storing and managing data, based on Hierarchical Data Format (HDF). An HDF5 file appears to the user as a directed graph. The nodes of this graph are the higher-level HDF5 objects that are exposed by the HDF5 APIs: Groups, Datasets, Named datatypes. Currently supported by the Python MDTraj package. 1.11 h5 HDF5 is the new version, according to the HDF group, a completely different technology (https://support.hdfgroup.org/products/hdf4/ compared to HDF. Trajectory format (binary)