Yes, I understand that, and thanks for your input.

but...
What I mean is, imagine you have downloaded a dozen or so titles from PG.
Load them into calibre and it will properly display the book titles.
Fine so far, BUT there is no way of relating the book title to the filename.
calibre will display say "Pride and Prejudice Jane Austen" but there is no way of knowing that that book relates to say pxyz.mobi file.
Very difficult to explain this but hopefully someone will know what I am rambling on about !