The AttributeValue has value LinkToInstance if the model element has a link to an instance of a model object. In Instance AttributeType there are no TypeProperty DataType = xxx XML child elements.
Example: In QPR Modeling Client a flow has 'To' attribute which is a link to a process step or store instance.
<ModelAttributeType Name="To" AttributeType="LinkToInstance">
<FieldType Name="ElementName" DataType="string" />
<FieldType Name="ElementId" DataType="string" />
<FieldType Name="TypeName" DataType="string" />
<FieldType Name="TypeID" DataType="string" />
<FieldType Name="InstanceId" DataType="int" />
</ModelAttributeType>
<Attribute AttributeName="To">
<Record>
<Field Name="ElementName" Value="ExtModel" />
<Field Name="ElementId" Value="PG_PS36" />
<Field Name="TypeName" Value="Activity" />
<Field Name="TypeID" Value="PG_PS2" />
<Field Name="InstanceId" Value="1" />
</Record>
</Attribute>