Referring to the e-pub standards at
http://www.idpf.org/ one can easily determine the current standard for e-pubs.
Quote
".epub" is the file extension of an XML format for reflowable digital books and publications. ".epub" is composed of three open standards, the Open Publication Structure (OPS), Open Packaging Format (OPF) and Open Container Format (OCF), produced by the IDPF."
It has been our determination that neither Sigil nor E-pub check have updated their respective softwares to reflect the "current" standards. We have politely attempted to point this out recently to both developers we were basically told that they prefer to do it their way, rather than in accordance with published standards. While they are both free to do as they please, neither should be able to claim that they are in accordance with current e-pub standards as they are not!
While we like the software, we are forced to work around it as well!
Go figure
