schema for different complex elements based on attribute value

[user]

Hi,

I have the following xml

<rootElem>
<child type="Single">
<!-- if type is "single", then we can have only 1 of the
following element with default for directory as "1"
-->
<childOfChild>
<!-- More elements here -->
</childOfChild>
</child>
<child type="Multiple">
<!-- if type is "Multiple", then we can have more that one
of the following element. The contents of this element
is same as that of in the "Single" case
-->
<childOfChild>
<!-- More elements here -->
</childOfChild>
</child>
</rootElem>

How do i write a schema for this multiple child "type" condition, if at
all it is possible ?

Thanks
Am