Table of contents

Appendices

6.3 Uniqueness of Attributes

In XML documents conforming to this specification, no tag may contain two attributes which:

1. have identical names, or

2. have qualified names with the same [local part] and with [prefixes] which have been bound to [namespace names] that are [identical] .

add This constraint is equivalent to requiring that no element have two attributes with the same [expanded name] .

For example, each of the bad start-tags is illegal in the following:

<!-- http://www.w3.org is bound to n1 and n2 -->
<x xmlns:n1="http://www.w3.org" 
   xmlns:n2="http://www.w3.org" >
  <bad a="1"     a="2" />
  <bad n1:a="1"  n2:a="2" />
</x>

However, each of the following is legal, the second because the default namespace does not apply to attribute names:

<!-- http://www.w3.org is bound to n1 and is the default -->
<x xmlns:n1="http://www.w3.org" 
   xmlns="http://www.w3.org" >
  <good a="1"     b="2" />
  <good a="1"     n1:a="2" />
</x>