Open eBook (OEB), or formally, the Open eBook Publication Structure (OEBPS), is a legacy e-book format which has been superseded by the EPUB format.
It was "based primarily on technology developed by SoftBook Press"[2] and on XML.
OEB was released with a free version belonging to public domain and a full version to be used with or without DRM by the publishing industry.
Inside the package a defined subset of XHTML may be used, along with CSS and Dublin Core metadata.
The default file extension is .opf (OEB Package Format).