[KevinH]

Yes, Sigil has never done that since we moved away from that horrid old xml processor way back before Sigil 1.0.

As for id strings being named after the file itself, there is no need to do this, no one reading it will ever see it and the only thing to use it is the opf internally. All it has to be is unique.

Any "new feature" to re-id all files in the OPF would have to be done by a Sigil plugin, as it is not suitable for Sigil itself.

Perhaps you can convince a Sigil plugin developer to help you create one. Do not forget to properly update the spine if needed and to watch for smil and other things that use the ids for references such as metadata elements in the form of refines.