Re: 2.x minor version cohabitation I think we should allow one minor revision back along with "tip" minor version cohabitation (i.e. 2.2.x & 2.4.x), but with a clear termination point on the older version. Some kind of policy like:
The older minor release will be maintained in a deprecated state for 18 months from the time of integration of the newer minor release. After 18 months cohabitation and support of the older release will be dropped, and no new updates will be integrated. This message posted from opensolaris.org
