https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms764613(v=vs.85)

books.xsd

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            targetNamespace="urn:books"
            xmlns:bks="urn:books">

  <xsd:element name="books" type="bks:BooksForm"/>

  <xsd:complexType name="BooksForm">
    <xsd:sequence>
      <xsd:element name="book" 
                  type="bks:BookForm" 
                  minOccurs="0" 
                  maxOccurs="unbounded"/>
      </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="BookForm">
    <xsd:sequence>
      <xsd:element name="author"   type="xsd:string"/>
      <xsd:element name="title"    type="xsd:string"/>
      <xsd:element name="genre"    type="xsd:string"/>
      <xsd:element name="price"    type="xsd:float" />
      <xsd:element name="pub_date" type="xsd:date" />
      <xsd:element name="review"   type="xsd:string"/>
    </xsd:sequence>
    <xsd:attribute name="id"   type="xsd:string"/>
  </xsd:complexType>
</xsd:schema>