Public License (GPL). GPL compatibility The question of whether and when both licenses are incompatible sparked debates in the free software domain in 2004 to 2006. For instance, the FSF considered the CDDL incompatible to their GPL license, without going into detail until 2016. CDDL is one of several Open Source Licenses which are incompatible with GPL. This characteristics was inherited from the MPL 1.1 (fixed with the MPL 2.0 according to the FSF) and results from a complex interaction of several clauses; the root of the problem being GPL virality, similar to other cases of GPL incompatibility. Some people argue that Sun (or the Sun engineer) as creator of the license made the CDDL intentionally GPL incompatible. According to Danese Cooper one of the reasons for basing the CDDL on the Mozilla license was that the Mozilla license is GPL-incompatible. Cooper stated, at the 6th annual Debian conference, that the engineers who had written the Solaris kernel requested that the license of OpenSolaris be GPL-incompatible. Simon Phipps (Sun's Chief Open Source Officer at the time), who had introduced Cooper as "the one who actually wrote the CDDL", did not immediately comment, but later in the same video, he says, referring back to the license issue, "I actually disagree with Danese to some degree", while describing the strong preference among the engineers who wrote the code for a BSD-like license, which was in conflict with Sun's preference for something copyleft, and that waiting for legal clearance to release some parts of the code under the then unreleased GNU GPL v3 would have taken several years, and would probably also have involved mass resignations from engineers (unhappy with either the delay, the GPL, or both—this is not clear from the video). Later, in September 2006, Phipps rejected Cooper's assertion in even stronger terms. Similarly, Bryan Cantrill, who was on Sun at that time and involved in the release of CDDL licensed software stated in 2015 that he and his colleagues expected in 2006 the fast emergence of CDDL licensed software into the Linux ecosystem and the CDDL being not an obstacle. cdrtools controversy The GPL compatibility question was also the source of a controversy behind a partial relicensing of cdrtools to the CDDL which had been previously all GPL. In 2006, the Debian project declared the cdrtools legally undistributable because the build system was licensed under the CDDL. The author, Jörg