VitalSource supports the ePub standard. Below are helpful links to the external standards documentation specific to ePubs. EPUB is the distribution and interchange format standard for digital publications and documents based on Web Standards. These are published by the International Digital Publishing Forum.
ePub 3.0.1 Overview: http://idpf.org/epub/301
Current Index: http://www.idpf.org/epub/301/spec/epub-contentdocs.html
We recommend reviewing the details associated with building a compliant ePub 3 file. The VitalSource Bookshelf product will work with all compliant files.
Additionally, here are some other helpful VitalSource-specific links: