I was able to dig up some sample code, but it didn't compile

void Start()
        {
         XmlSchemaComplexType complexType;
         foreach (XmlSchemaType type in xs.SchemaTypes.Values)
         {
          complexType = type as XmlSchemaComplexType;
          if (complexType != null)
           TraverseParticle(complexType.ContentTypeParticle);
         }

         foreach (XmlSchemaElement el in xs.Elements.Values)
          TraverseParticle(el);
       }

       void TraverseParticle(complexType.ContentTypeParticle)  // <-- This
line is the offender
       {
         if (particle is XmlSchemaElement)
         {
          XmlSchemaElement elem = particle as XmlSchemaElement;

          if (elem.RefName.IsEmpty)
          {
           XmlSchemaType type = (XmlSchemaType)elem.ElementSchemaType;
           XmlSchemaComplexType complexType = type as XmlSchemaComplexType;
           if (complexType != null && complexType.Name == null)
            TraverseParticle(complexType.ContentTypeParticle);
          }
         }
         else if (particle is XmlSchemaGroupBase)
         { //xs:all, xs:choice, xs:sequence
              XmlSchemaGroupBase baseParticle = particle as
XmlSchemaGroupBase;
                 foreach (XmlSchemaParticle subParticle in
baseParticle.Items)
                   TraverseParticle(subParticle);
             }
       }

so I actually found a way to fix it up, changing the line in question to
"void TraverseParticle(XmlSchemaParticle particle)"

That code actually does what I need here.  I have added a delagate to be
called at every 'visit' in my code so I can 'do something' while I"m
traversing it at each node.  So, I think the problem with the example code
was a simple copy-paste error.  I know someone will run into this later at
some point so I figured I'd post it.