Nicolas Cellier wrote:
> Oh, I just noticed there is a #xIllegal ... Not really used.
> 
> Using #xIllegal as default type would raise the question of what
> character beyond ASCII can be considered a valid binary...
> 
> «¬­±·»¿×÷ eventually are good candidates for example
> Not sure about these ¢£¤¥§¶

Good question. I would vote for being somewhat conservative and instead 
of using xIllegal for potential binary values use something like 
xQuestionable which would raise an exception that client code could 
handle if needed (and if unhandled behave like xIllegal).

> My following question will be about
> Scanner>>typeTableAt: aCharacter
> 	^typeTable at: aCharacter charCode ifAbsent:[#xLetter]
> 
> I would tend to restrict this to
> 	^typeTable at: aCharacter charCode ifAbsent:[
> 		aCharacter isLetter
> 			ifTrue: [#xLetter]
> 			ifFalse: [#xIllegal]]
> 
> but we might want some more extended binary characters...
> And program with ideograms, not only letters...
> 
> Unless we restrict selectors to ASCII ?
> Are non ASCII selectors in use ?

Yes. Not in any standard Squeak images but I've seen non-ascii selectors 
in custom code (and I think it's perfectly reasonable).

Cheers,
   - Andreas