[tzs]

For most of the Western world, if you take the set of all commonly used characters in the language(s) that are widely recognized in each country and form their intersection, you'll have at least the Arabic numerals and plain A-Z.

If SSIDs were restricted to just those characters, it would be fine in the Western World. But of course there is more to the world than the West.

Question: do most or all non-Western languages also have small subsets of characters that would be fine to restrict SSIDs to? For instance, Wikipedia tells me that Persian is written with a 32 character alphabet, and Arabic uses 28 characters for its alphabet.

I'd expect that for every alphabet-based language, there is a similar base set of characters you could reasonably limit SSIDs too, and so avoid all the problems you get with allowing full Unicode.

How about the languages that use logographic writing systems, such as Chinese, Japanese, Korean, and Vietnamese? Do they all have reasonable (albeit probably very large) subsets SSIDs could be limited to that would avoid all their weird stuff that can happen in Unicode but still allow most reasonable names to be used?

[jmiserez]

Don't forget that some of these are left-to-right (e.g. Hebrew, Arabic). Words are rendered left-to-right, and early email software would just expect each word to be sent reversed so that simple RTL rendering could be used. UTF solves this (and many other issues) quite nicely.