Transient VTKHDF format questions

I’ve been able to create a working demo VTKHDF file of UnstructuredGrid type with transient CellData and PointData. But I have a couple lingering questions:

  1. How do I handle static CellData that isn’t indexed by time. Is it possible to simply omit the corresponding dataset in the Steps/CellDataOffsets group?

  2. If I have CellData for some time steps, but not all, the documentation for CellDataOffsets says, “In the absence of a data set, the appropriate geometry offsetting for the time step is used in its place.” I have no clue what that means.

  3. The documentation for Steps/NumberOfParts uses “NumberOfPartsPerTimeStep” in an arithmetic expression. Is that a formal HDF attribute? It’s not mentioned elsewhere. To get my demo to work I had to set the NumberOfParts array to all 1. (I’ve got a single partition – I assume “part” == “partition”.)

Thanks for your help!