This is actually a very good list to start discussing the problem of variants. In ICANN context, people often lapped all these layers as one and discussed issues revolving them as one single class. And if we draw vertical lines down, these issues could further be divided by different etymology of the scripts, or in our case, divided into different languages that is currently having issues. I would strongly argue that we should strictly focus on A1 and maybe to some extend A2 for the context of variant in our group. I hesitate we should be dealing with anything lower than that. 2011/6/20 Patrik Fältström <patrik@frobbit.se>:
A.1. Two characters in Unicode really are to be treated as being equivalent. I presume one could say that the Hangul SC/TC issues fall in that category. A.2. Two different spellings of the same word in the same script and same language, like color/colour.
In between A2 & A3, I would insert "two ways to describe the same concept in the same script and language, like shop and mall"
A.3. Same word in the same language in two different scripts (bulgarian) A.4. Same word in two different languages