Transfer Specific Parts
To transfer specific parts using the 
Generate Downstream Structure action, you need to create a custom attribute on the Part Usage link. After assigning a value to this attribute in BOM Transformer, the Generate Downstream Structure action identifies the parts with matching attribute values between the upstream and downstream structure and adds the child nodes of the matching upstream part under the matching downstream part. Additionally, you can specify the types or subtypes of the parts that should be transferred from upstream to downstream.
Generate Downstream Structure action, you need to create a custom attribute on the Part Usage link. After assigning a value to this attribute in BOM Transformer, the Generate Downstream Structure action identifies the parts with matching attribute values between the upstream and downstream structure and adds the child nodes of the matching upstream part under the matching downstream part. Additionally, you can specify the types or subtypes of the parts that should be transferred from upstream to downstream.Specifying Custom Attribute
To specify the custom attribute for matching the upstream and downstream structure, perform the following steps:
1. Create a custom attribute on WTPartUsageLink. For more information, see Creating a New Attribute.
2. Access the associativity.properties file located at Windchill/codebase/com/ptc/core/foundation/associativity.
3. Replace the default attribute name specified in the line <Property name="com.ptc.windchill.associativity.BomGenerationMatchAttribute" default="xyz"/> with the new attribute name.
You can then add a value to the newly created attribute in BOM Transformer. You need to customize the table view in the Uses tab to display the attribute.
Specifying Part Types
To specify the types of parts eligible for transfer, perform the following steps:
1. Access the associativity.properties file located at Windchill/codebase/com/ptc/core/foundation/associativity.
2. Add the required types to the com.ptc.windchill.associativity.BomGenerationTypeValidation property.
The default type specified for the property is wt.part.WTPart. The type cannot be blank.