On the US keyboard, there are two Alt keys; left and right. On most national keyboards there is a single Alt key on the left, and an AltGr (Alternate Graphic) key on the right. This AltGr key is often used as the ISO/IEC 9995 non-locking Level 3 select mechanism.
In the French keyboard shown in Figure 2, the characters which can be entered using the AltGr are shown in the lower right corner. For instance, to input the Euro character (€) on the French keyboard layout you would press the E key while holding down the AltGr key. ISO9995 does not define a Shift-AltGr level, but several of the Microsoft Windows keyboards and a number of de facto keyboard layouts are defined this way with a Level 4. The AltGr key assignment is normally engraved on the lower right quadrant of the key.