Position of the characters on the keys

The picture shows the four possible positions to which a character may be associated in a key.

The number of characters that may be typed with the computer keyboard is much higher than the number of physical keys on the keyboard itself. This is possible thanks to the modifier keys, that, while they are pressed, switch the character associated to each key by selecting it from a group made of two, three or four characters. The modifier keys are Shift (Maiusc on Italian keyboards) and AltGr. Pressed alone or in combination, they work according to the following switching of the character:

Modifier key pressed	selected character
none	1^st position
Maiusc	2^nd position
AltGr	3^rd position
AltGr + Maiusc	4^th position

The set of characters represented in the keyboard and their specific position in each key is also called charater map.

Other modifier keys are Ctrl and Alt but here they are not considered because they are conventionally used as shortcuts for invoking commands in programs. Simultaneous pressing of both Ctrl and Alt has the same effect as AltGr.