The XML serializations of large NeuroML models can be prohibitive to store. For such cases, NeuroML also includes support for saving models in the binary HDF5 format via the NeuroMLHdf5Writer in libNeuroML. The same format can be exported also from the Java API (example).
The format of the export is documented below:
Network is exported as a
networkHDF5 group with
notes, and the
temperature(optional) stored as attributes.
Population is exported as a group with id
population_<id of the population>with
propertytags stored as attributes.
Projection is exported as a group with id
project_<id of the projection>with
HDF5 NeuroML files can be read and processed by
pynml in the same way as XML files (see here for LEMS Simulation file examples which reference HDF5 NeuroML models).