The ODB data structure is designed as parts and instances. Even if parts and instances are not defined in the input file, Abaqus creates a part from the whole model and an instance of it in the ODB file. The ODB reader in HyperView supports ODB files that have one or more parts and instances of the ODB file.
However, if an INP file is read in with an ODB results file as output, only single parts and instances are supported.