<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="a" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="a" type="a:aType" xmlns:a="a"/>
  <xs:complexType name="aType" mixed="true">
    <xs:sequence>
      <xs:element ref="b:b" maxOccurs="unbounded" minOccurs="0" xmlns:b="b"/>
      <xs:element ref="notb:b" xmlns:notb="notB"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>