Thank you, I have been playing with selections in Paraview. The selections can be saved, but saving extracted selection saves the complete datasets (points with coordinates, cells with connectivity, with no reference to original one). However, all this data is already in the original dataset. Optimal approach would be only to store selected IDs. It seems to me that Paraview does not support loading standalone selections (with just IDs) so one needs to implement plugin for this. Will try to have a look on this in more detail.