There isn't text coding. The problem stems from the Microsoft-centric design of USB modifiers — there is no true AltGr code, so they have the convention (at the

There isn't text coding. The problem stems from the Microsoft-centric design of USB modifiers — there is no true AltGr code, so they have the convention (at the OS level) that left Alt is always Alt and right Alt is sometimes AltGr. A few early converters didn't grasp that left and right versions of the same modifier key could have different meanings, because nobody in their right mind would do that.