After Moodle 3.9 release, it's being planned to start working in parallel with 2 lines of development, each one leading to different major releases.

This implies changing some assumptions, about versions, branches, the names of both, and what's allowed or not on each development line.

This epic is about, at very least:

• Explain which the plan is, with all the details.
• Detect and add, as issues of this epic, all the points to be taken into consideration.
• Modify all the tools (mdlrelease, downloads, version checkers, tracker, CI...) which previous assumptions about versions, branches and names my be affected.
• Modify all the processes (releasing, tagging, branching, version "reservation"...) and their corresponding docs.
• Ensure that the effects of the change to the proposed are under control (new or adjust checks).
• Guarantee that CI is covering both development lines.
• Document and much as possible all the above..