This may have to be referred to unpacker coders, but:
Imported from a KF8 using the KindleImport plugin, and every file had code like this:
Which of course caused epubcheck to error since the numeric id is illegal (giving the obscure "without colons" message).
the toc.ncx was fine though, it had
Code:
<navPoint id="np_4" playOrder="4">
Can these ids be made conformant when the epub is created?