The first draft of the Definition of Free Cultural Works was published 3 April 2006.

The Definition of Free Cultural Works is used by the Wikimedia Foundation.

Definition of Free Cultural Works (freedomdefined.org)

Thus, some within the movement only consider a few Creative Commons licenses to actually be free based on the Definition of Free Cultural Works.

The NC and ND options will make a work non-free according to the Definition of Free Cultural Works.

These restrictions are in contradiction with the Definition of Free Cultural Works or Free content, so these textbooks cannot be considered free textbooks.

The Definition of Free Cultural Works is a definition of free content put forth by Erik Möller and published on the website freedomdefined.org.