- The hook above.
- A diacritical mark of the Latin script, called dấu hỏi (“asking mark”) in Vietnamese, and found on Ả/ả, Ẳ/ẳ, Ẩ/ẩ, Ẻ/ẻ, Ể/ể, Ỉ/ỉ, Ỏ/ỏ, Ổ/ổ, Ở/ở, Ủ/ủ, Ử/ử and Ỷ/ỷ. Used to indicate mid falling-rising, harsh tone.
In some dialects of Vietnamese, particularly Saigonese, the mid-rising, glottalized tone represented by ~ is conflated with the mid falling-rising, harsh tone. Therefore, speakers of Saigonese often use this tone mark in words that are spelled with ~ in standard written Vietnamese.