Looking for SAML 1.1 Metadata XML schema file

[shibboleth655 at lewenberg.com]

We run a Shibboleth IdP and get SP metadata submissions from many 
service providers. We try to automate the validation of all our SP 
metadata using an XML Schema Definition (.xsd) file. We have been 
successful doing this with SP metadata using the namespace 
urn:oasis:names:tc:SAML:2.0:metadata.

However, we sometimes get SP metadata using the name space 
urn:oasis:names:tc:SAML:1.1:metadata. For example, the metadata file 
would start with this:

<md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:1.1:metadata" ... >

I cannot find an .xsd file for the urn:oasis:names:tc:SAML:1.1:metadata 
namespace. How can I validate such metdata? Does anyone have a copy of 
that schema definition?

Thanks in advance.