Hello! Our team utilizes a custom version of tzcode and a calendar utility that don't support negative DST offsets that was brought back in 2018e nor the 2018f fallback transactions Japan rules that were at 25:00 hour. We utilized 2018i rearguard-format version and we were able to utilize 2018i with our parsers. The 2018i announcement mentions that the rearguard is intended to be a temporary transition aid; that raises fear if we have to patch one of the upcoming tzdata releases that don't provide a rearguard with similar fixes. While we are planning to work on fixes for our timezone parsers; in order to ensure we have enough leeway for our new solutions, we would be curious to know how long will these rearguard versions (with no negative offsets) continue to be provided?