protected virtual QilNode VisitNamespaceDecl(QilBinary n) { return VisitChildren(n); }

 public XmlQueryType CheckNamespaceDecl(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.StringX);
     CheckXmlType(node.Right, XmlQueryTypeFactory.StringX);
     return XmlQueryTypeFactory.Namespace;
 }

 public XmlQueryType CheckXsltCopy(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtf);
     CheckXmlType(node.Right, XmlQueryTypeFactory.NodeS);
     return XmlQueryTypeFactory.Choice(node.Left.XmlType, node.Right.XmlType);
 }

 public XmlQueryType CheckDeref(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtf);
     CheckXmlType(node.Right, XmlQueryTypeFactory.StringX);
     return XmlQueryTypeFactory.ElementS;
 }

 public XmlQueryType CheckAttributeCtor(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.QNameX);
     CheckXmlType(node.Right, XmlQueryTypeFactory.NodeNotRtfS);
     return XmlQueryTypeFactory.UntypedAttribute;
 }

 public XmlQueryType CheckAfter(QilBinary node) {
     return CheckIs(node);
 }

 public XmlQueryType CheckAttribute(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtf);
     CheckXmlType(node.Right, XmlQueryTypeFactory.QNameX);
     return XmlQueryTypeFactory.AttributeQ;
 }

 public XmlQueryType CheckIntersection(QilBinary node) {
     return CheckUnion(node);
 }

 public XmlQueryType CheckDifference(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtfS);
     CheckXmlType(node.Right, XmlQueryTypeFactory.NodeNotRtfS);
     return XmlQueryTypeFactory.AtMost(node.Left.XmlType, node.Left.XmlType.Cardinality);
 }

 public XmlQueryType CheckOr(QilBinary node) {
     return CheckAnd(node);
 }

 public XmlQueryType CheckUnion(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtfS);
     CheckXmlType(node.Right, XmlQueryTypeFactory.NodeNotRtfS);
     return DistinctType(XmlQueryTypeFactory.Sequence(node.Left.XmlType, node.Right.XmlType));
 }

 //-----------------------------------------------
 // boolean operators
 //-----------------------------------------------
 public XmlQueryType CheckAnd(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.BooleanX);
     CheckXmlType(node.Right, XmlQueryTypeFactory.BooleanX);
     return XmlQueryTypeFactory.BooleanX;
 }

 protected virtual QilNode VisitXsltCopy(QilBinary n) { return VisitChildren(n); }

 protected virtual QilNode VisitRtfCtor(QilBinary n) { return VisitChildren(n); }

 public XmlQueryType CheckLe(QilBinary node) {
     return CheckNe(node);
 }

 public XmlQueryType CheckAdd(QilBinary node) {
     CheckNumericX(node.Left);
     CheckNumericX(node.Right);
     CheckNotDisjoint(node);
     return node.Left.XmlType.TypeCode == XmlTypeCode.None ? node.Right.XmlType : node.Left.XmlType;
 }

 //-----------------------------------------------
 // node comparison operators
 //-----------------------------------------------
 public XmlQueryType CheckIs(QilBinary node) {
     CheckXmlType(node.Left, XmlQueryTypeFactory.NodeNotRtf);
     CheckXmlType(node.Right, XmlQueryTypeFactory.NodeNotRtf);
     return XmlQueryTypeFactory.BooleanX;
 }

 public XmlQueryType CheckSubtract(QilBinary node) {
     return CheckAdd(node);
 }

 public XmlQueryType CheckBefore(QilBinary node) {
     return CheckIs(node);
 }

 public XmlQueryType CheckMultiply(QilBinary node) {
     return CheckAdd(node);
 }