Ubuntu Kylin is official flavour and is built solely using the ubuntu archive, same as used to build ubuntu desktop/server editions and other flavours. Kylin images are now generated in the canonical datacenter along the rest of the images. No outside code is allowed. At the moment many features of Kylin images target desktop market and better l10n (integration with local music stores, data providers, optimizing defaults, etc) See Kylin launchpad blueprints for more details.