When a critical problem is found in ICU libraries, we try to fix the problem in the latest development stream first. If there is a demand for the fix in a past release, an ICU project developer may escalate the fix to be integrated in the release to the ICU project management committee. Once the committee approved to merge the fix into back level stream, the developer can merge the bug fix back to the past release suggested by the committee. This merge activity must be tracked by maintenance release place holder tickets and the developer should provide original ticket number and description as the response in each maintenance ticket. These fixes are automatically included in a future ICU maintenance release.
Once a major version of ICU library is released, we create maintenance release place holder tickets for the major release (one for C, one for J). The ticket should have subject: "ICU4[C|J] m.n.X". For example, after ICU 4.8 release, we create two tickets - "ICU4C 4.8.X" and "ICU4J 4.8.X". These tickets must use the target milestone - "maintenance-release".
When the ICU project committee agree on releasing a new maintenance release, the corresponding place holder ticket will be promoted to a real maintenance release task ticket. This is done by following steps.