Multiple attributes and attributeGroups

In a complexType, can you have multiple declarations of attributes and/or
attributeGroups? For example, is this schema valid:

<?xml version="1.0" encoding="utf-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2000/10/XMLSchema">
  <xsd:element name="Author">
    <xsd:complexType>
      <xsd:sequence>
        <!-- some elements -->
      </xsd:sequence>
      <xsd:attributeGroup ref="Id"/>
      <xsd:attribute name="website" type="xsd:string"/>
      <xsd:attributeGroup ref="Genre"/>
      <xsd:attribute name="Living" type="xsd:boolean"/>
    </xsd:complexType>
  </xsd:element>
  <xsd:attributeGroup name="Id">
    <xsd:attribute name="Name" type="xsd:string"/>
    <xsd:attribute name="Num" type="xsd:integer"/>
  </xsd:attributeGroup>
  <xsd:attributeGroup name="Genre">
    <xsd:attribute name="Preferred" type="xsd:string"/>
    <xsd:attribute name="Secondary" type="xsd:string"/>
  </xsd:attributeGroup>
</xsd:schema>

-BKN