Overview of Generate Downstream Structure Action
When working on large engineering BOM structures, you can automate the process of generating a manufacturing BOM from a design BOM. The 
Generate Downstream Structure action, available in the middle pane tool bar of BOM Transformer, generates a downstream structure from an upstream structure using a customizable logic.
Generate Downstream Structure action, available in the middle pane tool bar of BOM Transformer, generates a downstream structure from an upstream structure using a customizable logic.The default logic transfers specific parts to the downstream structure and then restructures them according to the various embedded scenarios. You can configure this default logic using a set of properties in the associativity.properties.xconf file or customize it completely through the delegate framework.
For more information on configuring and customizing automatic BOM transformation, see Configuring and Customizing Automatic BOM Transformation.
You can also derive the root and assembly nodes for the manufacturing BOM from a template, and specify the rules that should apply when transforming the design BOM structure under the new nodes added in the manufacturing BOM.
• Template: A template can be any of the following:
◦ Part structure with an associated document that contains the rules for transformation.
◦ Part structure without an associated document.
◦ Document containing the rules for transformation.
• Rules: A text file in JSON format that specifies the rules to be applied when transforming an upstream structure to the downstream structure.
◦ The rules can based on matching attribute values on part, usages, or occurrences. For example, if the attribute value of an upstream child part matches the attribute value of a downstream assembly, transform the child part under the matching assembly.
◦ The rules can also specify the creation of equivalent links between the upstream and downstream structures.
 | If the rule file is not available, the properties specified in the associativity.properties.xconf file are considered for generating the downstream structure. |
For more information on generating the downstream structure, see Generating a Downstream Structure and Use Cases: Generate Downstream Structure.
Best Practice
The following are some best practices and information that is helpful when you use the Generate Downstream Structure action:
Generate Downstream Structure action:• Use the Generate Downstream Structure action only once on a selected assembly.
Generate Downstream Structure action only once on a selected assembly.• For properties that involve mapping, specify unique values in mapping attributes. For example, <AddToProperty name="com.ptc.windchill.associativity.reconciliation.addusage.wt.part.WTPart" value="attributeMapping.rule1=attribute1:String1:attribute2:String2"/>.
• Specifying a target type property in the associativity.properties.xconf file is prerequisite to using this action. The property file is located at Windchill/codebase/com/ptc/core/foundation/associativity.
For example:<AddToProperty name="com.ptc.windchill.associativity.reconciliation.addusage.wt.part.WTPartUsageLink" value="targetType=wt.part.WTPart"/>
• When this action is initiated on an assembly such as Axle Assembly, the application traverses the structure under Axle Assembly and generates a downstream structure for parts under the Axle Assembly.
• This action is disabled when you select invalid objects like part master, extended data, standard control characteristics, and so on.
• You can create new attributes and use those attributes in properties defined for this action.
• This action supports global, local, and calculated attributes in Windchill. The Boolean, string, real number, integer attributes are also supported. However, the date attribute is not supported.