Shift key
VNI invented, popularized, and commercialized an input method and an encoding, the VNI Character Set, to assist computer users entering Vietnamese on their computers. The user can type using only ASCII characters found on standard computer keyboard layouts. Because the Vietnamese alphabet uses a complex system of diacritics for tones and other letters of the Vietnamese alphabet, the keyboard would need 133 alphanumeric keys and a Shift key to cover all possible characters.