上じょう位い互ご換かん性せい

noun

downward compatibility; backward compatibility

Technical term for compatibility with older or lower-tier systems, versions, or components. Often used in IT and engineering contexts.

See also: 下位互換性 · 後方互換性

• このソフトウェアは上じょう位い互ご換かん性せいがあるので、古ふるいファイルも開ひらけます。

  This software has backward compatibility, so it can open old files.

noun

upward compatibility; forward compatibility

Often considered an incorrect usage; the intended meaning is actually downward/backward compatibility. The term 上位互換性 literally suggests compatibility with higher-tier systems, but in practice it is frequently misused to mean the opposite. Learners should be aware of this common confusion.

See also: 下位互換性

• 「上じょう位い互ご換かん性せい」を前ぜん方ぽう互ご換かん性せいの意い味みで使つかうのは誤ご用ようとされることが多おおい。

  Using 上位互換性 to mean forward compatibility is often considered a misuse.