non-ascii namespace name question

John Cowan cowan at
Mon Sep 13 15:52:10 BST 1999

Takuki Kamiya scripsit:
> I have encountered a usage of namespace'd XML where namespace name (i.e. URI)
> contains non-ascii characters, and is wondering how namespace-aware XML software
> should handle the URIs.
> As an example, think of the instance shown below.
> <x xmlns:ns1="http://www.&#x5BCC;&#x58EB;&#x901A;" 
>    xmlns:ns2="" >
>   <good n1:a="1"  n2:a="2" />
> </x>
> Both of the URIs conceptually denotes "" except that
> the part "fujitsu" is represented by using numeric character references in the
> first case and is represented as being encoded as mentioned in XML 1.0 spec.
> (I mean "4.2.2 External Entities")

Technically, the first URI is not conforming, because the surface form of
an URI can only contain plain ASCII.  However, applications should
treat such an URI as identical to the URLencoded UTF-8 in the second

> My question is, is a namespace-aware XML processor supposed to identify the
> two URLs shown above as identical ones so that the XML instance above is in
> error since n1:a and n2:a really means the same?


> If the answer to the question is "yes", then I believe XML processors should
> return encoded representation such as ""
> to using applications as namespace name. Is my understanding correct?

It's a reasonable thing to do as a matter of error recovery.
An alternative action is to reject the URI as ill-formed.

John Cowan                                   cowan at
       I am a member of a civilization. --David Brin

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