Namespace prefixes optional?

David Megginson david at
Fri Jan 7 00:22:54 GMT 2000

Bob Kline <bkline at> writes:

> I'm still trying to absorb all of the intricacies of namespaces, and I
> can see I have a long way to go.  I'm looking at the XLink
> recommendation ( and I see the following:

Here are the tricky points about Namespaces:

1. Namespace URIs are just unique identifiers, like Java or Perl
   package names; they don't (necessarily) point to anything.

2. There can be a default Namespace for element names but not for
   attribute names.

3. Not withstanding #2, some apps may treat unprefixed attribute names
   as if they belong to the same Namespace as the corresponding
   element name.

Anything I'm missing?  If you want to run through a quick Q-and-A to
make sure you've got it, take a look at the following:

Sure, the stuff about per-element Namespace partitions and global
attributes is confusing, but it's non-normative and you can safely
ignore it.

>   A sample set of declaration for a series of elements that use the
>   type attribute might look as follows:
>     <!ELEMENT student EMPTY>
>     <!ATTLIST student
>       xlink:type     (locator)     #FIXED "locator"
>       xlink:href     CDATA         #REQUIRED
>       xlink:role     NMTOKEN       #FIXED "student"
>       xlink:title    CDATA         #IMPLIED
>     >
>     . . . .
>   The following example shows how an XML document using these
>   declarations might look:
>     <student
>       href="/students/patjones.xml"
>       title="Pat Jones" />
>     . . . .
> Does this mean that once the namespace prefix has been declared in the
> DTD the parsers understand that (for example) "href" really means
> "xlink:href" (and therefore this sample document will be valid)?

To me, that looks very much like a typo.  I would have expected

    xlink:href = "/students/patjones.xml" 
    xlink:title="Pat Jones" />

All the best,


David Megginson                 david at

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