In certain cases it may be useful to get information about where in the archive the stream starts and ends. Typically when zip is used as resource container and the resources are then mapped directly into memory, but not only.
The size and compressed size are already available but not the stream offset.
This can be applied to other archive types as well, therefore it would make sense to put this into basic interface - ArchiveEntry. But not necessarily all of them have to support it.