[KevinH]

No. It is not a bug. I will check to see if the manual needs to be updated but that only happens once every couple of Sigil releases, as getting volunteers to help update our user guide is next to impossible.

There is no requirement to base manifest ids on filenames at all. The only spec is that the manifest id be unique. Some epub publishers use uuids here for that reason.

In order to support mass renaming of thousands of files, and because the approach used to rename ids in older versions of Sigil only worked for epub2 (it was broken in epub3 and could introduce subtle errors), Sigil decided to stop changing still unique manifest ids when renaming files. This happened quite a while back.

For those people who insist to create unique manifest ids from current filenames, we recently added in a new tool to rebase all ids on current filenames if the user so chooses. It properly handles both epub2 and the more complex epub3 correctly.

I am thinking about creating a tool that will assign uuids instead.

And finally you control the default naming scheme for new files, and can set a template file that loads the template/blank epub you specify.