They dump or restore list users (members, owners or editors) in database from/to file.

[change] File for members was changed to `<list dir>/member.dump` which will replace:
  - `subscribers` (used by Sympa prior to 5.4a.1)
  - `subscribers.db.dump` (generated by dump command)
  - `subscribers.closed.dump` (backup for closed list)
[change] Additional files to dump owner or editor: `<list dir>/owner.dump`, `<list dir>/editor.dump`.
They will be used as initial (permanent) owners/editors, or as backup for closed list
[*change] owner and editor parameters in list config file are no longer sync with actual owners/editors.  They are used only at the time of installation of list.