There's been a clear need expressed to support tzdb users who would rather not deal with the effects of the recently-proposed alike-since-1970 patch. On the other hand there are also fairness and guideline-oriented reasons for the patch, which was originally discussed and installed with more than our usual care and review. Because of the extensive followup discussions I don't see how a single version could be appealing to both sides of this disagreement. So I propose we add a Makefile or similar build-time option to let tzdb users have it either way. Set the flag one way, and it will be as if the recently-proposed changes did not occur. Set it the other way, and you'll get the changes. This will be similar to our vanguard/rearguard support, which helped address a similar disagreement back in 2018. We could even control things via the existing vanguard/rearguard build-time option; that might be simpler. If you have ideas about what the the option's specific effects should be, please let me know. If there is support for this idea, I expect to be able to implement this option soon, in plenty of time before any urgent change due to a real-world rule change arrives. Like most compromises, I expect this approach to not be entirely satisfactory to anybody. However, I hope it helps us move forward together.