Wāpuro rōmaji (ワープロローマ字), or kana spelling, is a style of romanization of Japanese originally devised for entering Japanese into word processors (ワードプロセッサー, wādo purosessā, often abbreviated wāpuro) while using a Western QWERTY keyboard.
[1] Wāpuro rōmaji is now frequently employed in general-purpose computer input as well as word processing, but the name lives on.
Some conventions, however, differ from standard romanizations: Unlike Kunrei and Hepburn, wāpuro style is based on a one-to-one transcription of the kana.
[1] Wāpuro thus does not represent some distinctions observed in spoken Japanese, but not in writing, such as the difference between /oː/ (long vowel) and /oɯ/ (o+u).
Likewise, the irregularly spelled particles wa (は), e (へ) and o (を) must be entered as written (ha, he and wo respectively), not as pronounced (unlike Kunrei and Hepburn, which transcribe the pronunciation).