By using DocBook. Basically CK-12 is bringing the power of single source to textbooks and putting it all in the hands of the teachers. You can create a Flexbook to suit your class needs, download it from Flexr, and then plug it into LiveTechDocs to review it efficiently and conveniently in collaboration with other teachers,

Sharing XML documents during the writing and review process is a missing link in the XML publication chain. While Office or PDF applications help, they also add another extra-layer of complexity and loose the “XML awareness” of our initial document. That’s where LiveTechDocs comes into play.