 They are written with two voiceless letters, "pp", "tt" and "kk" when they occur between two vowels.Since the length of closure is defined in terms of time between the closure of the vocal tract after the preceding vowel, and the release before the following vowel, stops at the beginning or end of a word do not have a fortis-lenis contrast.Orthographically in Wagiman, word-initial stops are written using the voiced Roman letters ("b", "d" and "g"), but at the end of a word, voiceless letters ("p", "t" and "k") are used instead.