How are "Roles" used in the National Information Exchange Model (NIEM)?

Usage of Roles can be demonstrated via the following example:

<Person s:id="P1">
   <PersonName>
      <PersonFullName>Fred Smith</PersonFullName>
   <PersonName>
</Person>

<EnforcementOfficial>
   <RoleOfPersonReference s:ref="P1"/>
   <EnforcementOfficialBadgeID>
      <ID>101101</ID>
   </EnforcementOfficialBadgeID>
</EnforcementOfficial>

From the above example, it is clear that Fred Smith has a "Role", and that role is of an EnforcementOfficial.