A friend of mine reads his eBooks on Android systems and informed me that the Atlantis made eBook would not open in Android using either Aldiko, FBReader, or some other readers. He said the same eBook would open on his PC in ADE. I tried the same book on my iPad and it was ok using several readers. I opened the eBook in Sigil and resaved it with no changes and then it would open fine on his Android system with any of his eBook readers. I have no idea why this would be so although Sigil did a bit of rearranging as it always does.