Polynesian languages like Māori, Samoan and Niuean use macrons to mark long vowels. There are different ways you can insert macrons when you type on a computer, including through the use of codes such as Alt + 0257 for ā and Alt + 0275 for ē. The easier option, and one that can be used outside of the Microsoft Word environment, is setting up your input language as English (New Zealand) and using the Māori keyboard.
All you need to do then is press the ~ key (top left of the keyboard) followed by the relevant vowel.
macronˈmakrɒn/nounplural noun: macrons
- a written or printed mark (¯) used to indicate a long vowel in some languages, or a stressed vowel in verse.