// declare XML Schema namespace to be xs, but allow the user to override it.
// if 'xs' is used for other things, we'll just let TXW assign a random prefix
if(!xmlNs.containsValue(WellKnownNamespace.XML_SCHEMA)
&& !xmlNs.containsKey("xs"))
schema._namespace(WellKnownNamespace.XML_SCHEMA,"xs");
schema.version("1.0");
if(uri.length()!=0)
schema.targetNamespace(uri);
// declare prefixes for them at this level, so that we can avoid redundant