i want to ref an attribute to an attribute, so i can make a restriction on the user that he won't forget to write an attribute that does not have a same attribute in another tag  

example:  

invalid:(because there are no tag named `word` that has the attribute `B`

```
<model name="A"/>
<model name="B"/>
<word key="A">
    <value lange="english">Add</value>
    <value lange="frensh">ajouter</value>
</word>

```

valid:

```
<model name="A"/>
<model name="B"/>
<word key="A">
    <value lange="english">Add</value>
    <value lange="frensh">ajouter</value>
</word>
<word key="B">
    <value lange="english">Add</value>
    <value lange="frensh">ajouter</value>
</word>

```

can that be done in xsd ?