title: How to indicate that an xml schema that requires schema 1.1 features?
body: <p>If I create an XML Schema that requires schema 1.1 features (especially subtle ones, like removing an optional element in restriction of a base type), what is the best way to indicate that this schema should not be used with a processor that only understands version 1.0?</p>
  
  <p>In an XSLT stylesheet file, it is possible to indicate the version of the XSLT specification that is used using a <code>version</code> attribute.</p>
  
  <p>But in an XSD file, the <code>version</code> attribute does not have this meaning - it is a free-form attribute that says something about the version of the schema, not about the version of the specification that is being used.</p>
  
  <p>And is it <em>required</em> to label a schema that uses 1.1 features?</p>
  
  <p>I have a complex set of schemas using the FPML 5.5 specification and some custom schemas, and it cannot be validated with some schema validators, but I'm not sure if that is because the validator has bugs or because the schema is subtly using xml schema 1.1 features.</p>