Protocol Action: 'Right-to-left scripts for IDNA' to Proposed Standard

Vint Cerf vint at google.com
Mon Feb 15 15:59:49 CET 2010


I think it might be rather hard for the IRI cases because strings that  
appear after the domain name (or URN) in an HTTP expression have  
little limitation. In fact, there are lots of applications that try to  
be smart about recognizing domain names for email or URLs - and guess  
wrong, create inappropriate links, etc. anything of the form "www...."  
often gets picked up as a domain name and some domain names without  
the "www" are not marked as web links...

vint

On Feb 14, 2010, at 11:31 PM, Abdulrahman I. ALGhadir wrote:

> A question about this:
> >However, it is possible and conformant to UBA to have a higher  
> level protocol that reorders labels in a domain name, >and in the  
> path, and in the query, because it allows for such specialized  
> overrides specifically. So you could take the >following internal  
> string with characters from left to right
>
> How hard is it to make higher level(a standard sort of) either to be  
> part of Unicode or something else for recognizing strings of type  
> <something>@<something> , <protocol>://<something> ,.. all of  IRI   
> strings?.
>
> Abdulrahman,
>
>
> From: mark.edward.davis at gmail.com  
> [mailto:mark.edward.davis at gmail.com] On Behalf Of Mark Davis ?
> Sent: 14/Feb/2010 11:23 PM
> To: Michel Suignard
> Cc: Shawn Steele; Slim Amamou; Abdulrahman I. ALGhadir; idna-update at alvestrand.no 
> ; Aharon (Vladimir) Lanin
> Subject: Re: Protocol Action: 'Right-to-left scripts for IDNA' to  
> Proposed Standard
>
> A few comments on remarks here:
>
> >Well as we know the IDNA protocol didn't adapt bidi algorithm (UAX  
> #9) fully. They disallowed all bidi markers (LRM,RLM,...) which are  
> they used to solve problems from this kind.
>
> > Well I don't think so it can be done in UAX#9 (well if URI has its  
> own rules) the UAX#9 does know about the nature of characters  
> (Neutral,RTL,LTR,week..) the context direction etc.. and thus there  
> are possible ways to fix this issues in UAX#9 rather than IDNA itself.
>
> Changing UAX#9 (aka UBA) at this point would be very difficult,  
> because of stability concerns. We've seen before where very minor  
> changes to it have caused many problems for users, because it  
> changes the layout of existing documents. While not impossible, one  
> would have to make a very good case for the change, and be prepared  
> to demonstrate, with compelling data, that the benefit would be  
> worth the cost.
>
> The UBA was designed for plain text, not special syntax. And no  
> matter how it was structured, it was always clear that one would  
> need to be able to override the default; to that end, the marks and  
> overrides were added. Because those are disallowed in IDNA, this  
> tool is not available, however.  The reason to not allow those in  
> IDNA was because of the opportunity for constructing, artificially,  
> very confusable IRIs.
>
> (BTW Looking back at it, one of the problems with the UBA was that  
> it tried to do too much. There is a tension between heuristics and  
> predictability, and if we could go back in time and redo it, one of  
> the things I'd change would be to reduce the heuristics, especially  
> around numbers, so as to make it more predictable for users.)
>
> However, it is possible and conformant to UBA to have a higher level  
> protocol that reorders labels in a domain name, and in the path, and  
> in the query, because it allows for such specialized overrides  
> specifically. So you could take the following internal string with  
> characters from left to right
>
> http://a.B.C.d/e/F/G/h?i=J&K=l&M=n&o=P
>
> and have them display
>
> ...F/e/d.C.B.a//:http
>
> This would be possible, but is not necessarily a good idea. The  
> problem comes in the interaction between those environments that (a)  
> look for IRIs and handle them this way, and (b) environments that  
> don't parse for IRIs, or don't recognize them or their fragments, or  
> don't display them in the 'new' way once they have them. There is  
> already the issue of display being different in RTL vs LTR  
> paragraphs; you don't want typing in one environment within RTL to  
> give yet different results than in another within RTL.
>
> And we know that recognizing IRIs (and fragments thereof) occurring  
> in plain text is difficult. You don't wantPAYPAL.JOE.com to appear  
> as PAYPAL.JOE.com in my email, and JOE.PAYPAL.com in the address  
> bar, and so on.
>
> So any design for having a special ordering for IRI BIDI elements  
> has to take a host of issues into account. I'm not saying that it  
> can't be done, but it is a big job, and any transition has be be  
> extremely carefully considered. Various people in Unicode have  
> considered it at one time or another, but we've just never seen a  
> clear path forward.
>
> Mark
>
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