glyph order

Chatacter sets for Opentype random contextual alternates


Due to I found out how I can program an opentype feature for random contextual alternates. (If anybody is interested and didn´t find it yet:

this is the code I found:

feature salt {
lookup rotate {
sub @set_1 @set_1' by @set_2;
sub @set_2 @set_1' by @set_3;
sub @set_3 @set_1' by @set_4;
sub @set_4 @set_1' by @set_5;
sub @set_5 @set_1' by @set_1;
} rotate;
lookup rotate;
} salt;

Yet, I wonder in which order I should put the charakter sets to make it work.
Do I have to do it like this: A, A.alt1, A.alt2, A.alt3, B, B.alt1, B.alt2, B.alt3
or rather A-Z, then A.alt1-Z.alt1 and so on?