Language input keys, which are usually found on Japanese and Korean keyboards, are keys designed to translate letters using an input method editor (IME). On non-Japanese or Korean keyboard layouts using an IME, these functions can usually be reproduced via hotkeys, though not always directly corresponding to the behavior of these keys.
Keys for Japanese Keyboards
The OADG 109A and older 109 keyboard layouts which are the standard for Microsoft Windows have five dedicated language input keys:[1]
halfwidth/fullwidth/kanji (hankaku/zenkaku/kanji 半角 / 全角 / 漢字) at the top left key of the keyboard;
alphanumeric (eisū 英数), combined with non-language specific key ⇪ Caps Lock;
non-conversion (muhenkan 無変換), on the left of the space bar;
conversion (henkan 変換), on the right of the space bar;
katakana/hiragana/rōmaji (カタカナ / ひらがな / ローマ字), on the right of the space bar, next to 変換.
Apple keyboards designed for Mac OS X have two language input keys: alphanumeric (英数) and kana (かな).
The keyboards for NECPC-9800 series, which was dominant in Japan during the 1980s and early 1990s, have three language input keys: kana, NFER (no transfer, same as nonconversion), XFER (transfer, same as conversion).[2]
For non-Japanese keyboards, the following shortcuts can be used for typing Japanese on English keyboard with Windows:
Alt + Shift switch between languages (IMEs)
Ctrl + Caps Lock switch to Hiragana
Alt + Caps Lock if in alphanumeric mode change to Hiragana, then switch to Katakana
Half-width/Full-width/Kanji (半角 / 全角 / 漢字, hankaku/zenkaku/kanji) toggles between entering half-width or full-width characters (if 2 versions of same character exists), and also between IME on (for Japanese, see Kanji key) and off (for English, see Alphanumeric key). Prior Windows 98 and older systems, the key was only with Half-width/Full-width function.
Kanji
Used to switch between entering Japanese and English text. It is not found as a separate key in the modern Japanese 106/109-key keyboard layout. On the Common Building Block (CBB) Keyboard for Notebooks, as many 106/109-key keyboards, the Kanji key is located on the Half-width/Full-width key, and needs the key ALT.
It is found as a separate key on the IBM PS/55 5576-001 keyboard. On the IBM PS/55 5576-002 keyboard, it is mapped to the left Alt key.
Alphanumeric
Alphanumeric (英数, eisū) toggles alphanumeric characters. In the Japanese 106/109-key layout, it is located on the Caps Lock key. Pressing Alphanumeric/Caps Lock key alone actually means alphanumeric function, a user has to press ⇧ Shift+英数 / Caps Lock key to get caps lock function.
Conversion
Conversion (変換, henkan) is used to convert kana to kanji. In the Microsoft IME, Conversion selects conversion candidates on highlighted input, and ⇧ Shift+変換 is used to display the previous candidate, or zenkōho (前候補). The alt version of this key is also pronounced zenkōho (全候補), which means "all candidates", shows all input candidates.
Non-conversion
Non-conversion (無変換, muhenkan) specifies that the kana characters entered are not to be converted into kanji candidates.
Katakana/Hiragana/Rōmaji
Katakana,hiragana,rōmaji (ひらがな / カタカナ / ローマ字, katakana,hiragana,rōmaji) used to switch between hiragana or katakana characters. It can also be found for switching between hiragana, katakana and rōmaji as shown below. Alt+ひらがな / カタカナ / ローマ字 or Ctrl+⇧ Shift+ひらがな / カタカナ / ローマ字[3] (this feature is printed as Rōmaji (ローマ字) on the same key) toggles between rōmaji input and direct kana input in some IMEs (e.g. Microsoft IME).
カタカナ
ひらがな ローマ字
Keys for Korean Keyboards
The standard keyboard layout for IBM PC compatibles of South Korea is almost identical to the U.S. layout, with some exceptions:
On the top of the \ key, the backslash is replaced with the ₩ (Won sign) or both of them are printed. The backslash has the shape of the Won sign including system fonts such Gulim (굴림) and Malgun Gothic (맑은 고딕). Note that vertical bar | (⇧ Shift+\) is also replaced as the broken bar ¦ on some South Korean keyboards, but the broken bar in Unicode (U+00A6) is not inputted by most of Korean IMEs.
Keyboards with a small ← Backspace key and large "backwards-L" shaped ↵ Enter key are commonly used in South Korea.
There are two additional keys: 한/영Han/Yeong (or 한영HanYeong) and 한자Hanja (or 漢字Hanja) keys. They do not exist as independent keys on some keyboards.
Many computer systems support alternative keys or key sequences for keyboards without the Han/Yeong key. It is absent from the keyboards of most portable computers in South Korea, where the right Alt key is used instead. On the right Alt key of these devices, only "한/영" (Han/Yeong) or both "한/영" (Han/Yeong) and Alt are printed.
Hanja (한자)
It converts Hangul to Chinese characters (hanja) or some special characters.
Many computer systems support alternative keys or key sequences for keyboards without the Hanja key. It is absent from the keyboards of most portable computers in South Korea, where the right Ctrl key is used instead. On the right Ctrl key of these devices, only "한자" (Hanja) or both "한자" (Hanja) and Ctrl are printed.