Hi, Here's my 5 cents to the tzdb compatibility discussion: - Things need to move forward; half-measures like "functional comments" end up hurting in the long term and create unpredictable behavior. - There are other users of the tzdata "source" so compatibility needs to be maintained for "some time". - On the other hand, we can't be held hostage forever; people who write parsers, should be able to maintain the code. Straw man proposal: 1. Create a version ChangeLog with tzdb; it should be simple: - a version number (for reference) - the release date (to guide expiration) - an explanation to what changed in the format (for parser writers) 2. Maintain two copies of the source; the current one, and the previous version in a "compat" subdirectory. Expire "compat" a year after the release of the next version. I hope this is helpful, christos