<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified" attributeFormDefault="unqualified">
  <xs:element name="root" type="troot"/>
  <xs:complexType name="troot">
    <xs:sequence  maxOccurs="unbounded" minOccurs="0">
      <xs:sequence>
        <xs:element name="aaa" type="xs:string" maxOccurs="unbounded" minOccurs="0"/>
      </xs:sequence>
      <xs:sequence>
        <xs:element name="bbb" type="xs:string" maxOccurs="unbounded" minOccurs="0"/>
      </xs:sequence>
      <xs:sequence>
        <xs:element name="ccc" type="xs:string" maxOccurs="unbounded" minOccurs="0"/>
      </xs:sequence>
    </xs:sequence>
  </xs:complexType>
</xs:schema>