On the forest trail between Bukit Karamunting and Tasek Lama, there are two wasai ('waterfalls') named after two residents of Kampung Subok, Abin and Jumat. But the spelling of the first of these is uncertain. Look at the two signs just a few metres apart. On one, it is spelled Abin, and on the other, it is Aben.
This variability in the spelling might reflect two things:First, Brunei Malay only has three vowels, /i, a, u/. So it is uncertain how to spell Brunei names when the letters 'e' and 'o' are also adopted from Standard Malay spelling.
Second, and perhaps equally important, in Malay /i/ and /e/ cannot be contrastive in the final syllable of a word, just like /u/ and /o/ cannot be. This is why kasih ('love') is often pronounced with [e] in the final syllable, especially in the phrase terima kasih ('thank you'; lit. 'received with love'). It is also why we sometimes see the spelling kampung ('village') and at other times we find kampong, and it is why the Malay word amuk ('crazy') is borrowed into English as amok (as in 'run amok').