Minimal Permission Set:
<PermissionSet class="System.Security.PermissionSet"
               version="1">
   <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
                version="1"
                Flags="Execution"/>
</PermissionSet>


Optional Permission Set:
<PermissionSet class="System.Security.PermissionSet"
               version="1">
   <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
                version="1"
                Unrestricted="true"/>
</PermissionSet>


Refused Permission Set:
<PermissionSet class="System.Security.PermissionSet"
               version="1">
   <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
                version="1"
                Flags="SkipVerification"/>
</PermissionSet>