> a European national keyboard is by itself in general a keyboard group composed of three levels (one unshifted, one shifted, one obtained with AltGr).
In practice, the keyboards I have seen with an additional level generally need and use a pair of additional levels. The issue is that if a lowercase character x is on a level, then you want to be able to get the uppercase version of it X by using that same level plus a shift key. So in practice you end up with plain, plain+shifted, alternate, alternate+shifted.
[Alain] ... which means 2 groups of 2 levels in ISO terms.
Commercial keyboards in Europe (at least those using the Latin script) are limited to 3 levels in general (3 states: unshifted, shifted, or AltGr state). In general the third level is for special characters and not for letter pairs.
I'm just curious: what keyboards have you seen? Was it outside Europe or the two Americas? Or do you talk about virtual keyboards shown on a screen?
Of course if one needs to use other script beyond the Latin script (or many languages), one must go beyond 3 levels, i.e. beyond one group.
Alain LaBont�
Qu�bec
PS: Canadian national standard CAN/CSA Z243.200-92 uses 2 groups strictly for the Latin script, the first group with 3 levels, the second group with 2 extra levels (if you want to *not use* the "group" notion, this means 5 shifted states, 5 levels; fortunately the ISO framework has limited groups to 3 levels at once).
