upward compatibility; forward compatibility
Technical term for compatibility with higher-tier or newer systems. Often contrasted with 上位互換性 (backward compatibility).
このソフトウェアは下位互換性があるので、新しいバージョンで作成したファイルを古いバージョンでも開けます。
This software has forward compatibility, so files created in the new version can be opened in the old version.
downward compatibility; backward compatibility
Often used incorrectly to mean backward compatibility. The correct term for backward compatibility is 上位互換性. This sense is marked as incorrect usage.
See also: 上位互換性
Using 下位互換性 to mean compatibility with older devices is often considered a misuse.