With katakana, you can use the same diacritics and conventions used with hiragana. However, unlike in hiragana, in katakana long vowels are represented by adding an elongation mark (ー).

Note that the katakana system allows some combinations of characters that are not available in the hiragana system in order to approximate the pronunciation of foreign words.

Such examples include ファ (fa), フィ (fi ), フェ (fe), フォ (fo), ティ (ti),トゥ (tu), ディ (di), ドュ (du), ヴァ (va), ヴォ (vo),ヴェ (ve),ウォ (wo), ウェ (we), チェ (che), シェ (she), and ジェ (je).