> In what sense are those names taken?
> Are packages with those names included in Emacs, or in GNU ELPA?
> 
> If it simply means that people published files with those names, that
> doesn't mean the names are off limits for anyone else.  We can install
> a file in Emacs core or in GNU ELPA with either of those names.

Neither are in Emacs or GNU ELPA because the effort to do that is
prohibitively high for the majority of the Emacs community.  Sure, one
can ignore their existence, but that will make things confusing as one
needs to clarify whether they mean the package in Emacs/GNU ELPA or the
community one that preceded them.  Names are important after all and so
are communities.

> By the way, I know that your package can be used to read some ebooks,
> but that is all I know.  Could you please tell me just a little more?
> For instance, which formats does it aspire to handle?  Which formats
> does it handle now?

It handles standards-complying EPUB2 and EPUB3 ebooks.  I've considered
extending it to handle the FB2 format, but that would pretty much
require a full rewrite.