> 'Interrupted html documents are therefore lost 
during 
> an interruption.'
> 
> hmmmh... if those html files were lost during an 
> interruption, would they be recovered during 
updating 
> that mirrored site?
Yes, absolutely

> would httrack react like it's a 
> new material added to that site and then d/l it or 
not?
Yes, like new material, not yet referenced in the 
internal cache.