What are "opt-in flavors" during development cycle?

Question

Right now, 14.04 is in active development, the detailed Release Schedule of which is hosted here. One can see that the schedule says Alpha 1, Alpha 2 and Beta 1 are for opt-in flavors only.

Can someone please explain the concept of opt-in flavors? What are they and what is different compared to flavors which have opted-out? Who decides upon them and how do I know which flavors have opted-in for a particular development cycle? Do the flavors which have opted-in change between the Alphas and the Betas? And all the points which would help me understand why they are important and have a separate distinction.

Answer 1

Ubuntu has many derivatives, or 'flavors'.

Kubuntu, Xubuntu, Lubuntu are some of them. Each of these are maintained independently, by their communities. These variants have the freedom to participate in these alpha and beta releases, or have their own schedules, or skip some of them.

Usually, ubuntu as a project cares about only the officially recognized derivatives. Being an unofficial derivative means that it doesn't get access to some perks. For example, unofficial derivatives are off-topic on Ask Ubuntu.

To know if a project opted in, you need to check with the project itself.