Doubt about nav.xhtml and editor

Hi,

The new books with EPUB3 format (allegedly) usually includes a "nav.xtml" or similar file with links to the files in the book (it looks like another toc). If I rename a file in the editor, the file is renamed inside this document. If I remove it, however, it is not removed into the document and the check gives error.

Is it as intended? Is it a bug? Doesn't it matter? (A bit OCD, I don't like errors).

Thank your very much