Additional Windchill Capabilities > Manufacturing Process Management > Transforming an eBOM into an mBOM > Propagating Upstream Changes > Customizing the Comparison Mechanism
  
Customizing the Comparison Mechanism
Out of the box, the application supports two criteria to compare the current iteration of the upstream structure with the previous iteration: OutOfDateCriteria and DateBasedCriteria. By default, the application uses OutOfDateCriteria. In this, equivalence association is used as the criterion to compare the current iteration of the upstream structure with the previous up-to-date iteration that was linked to the current downstream structure. If no equivalent link exists between the current downstream structure and the previous iteration of the upstream structure, the comparison is performed between the current and the previous iteration of the upstream structure. You can change this default behavior to compare the current iteration with the previous version of the upstream structure using the property com.ptc.windchill.associativity.structure.compare.usePreviousVersion. The default value for this property is false.
You can customize the default behavior to perform the comparison based on time values using DateBasedCriteria. When set to time-based comparison, the current iteration of the upstream structure is compared with the iteration at a specific time. The time value is specified in the property file in the Windchill xconf directory. To configure the comparison capability to use time values, perform the following steps:
1. Open the associativity.service.properties.xconf file located at Windchill/codebase/com/ptc/windchill/associativity/xconfs.
2. Disable the configuration com.ptc.windchill.associativity.structure.compare.criteria.OutOfDateCriteria.
3. Enable the configuration com.ptc.windchill.associativity.structure.compare.criteria.DateBasedCriteria.
4. Open the associativity.properties.xconf file located at Windchill/codebase/com/ptc/core/foundation/associativity/xconfs.
5. Set the time value for the property com.ptc.windchill.associativity.structure.compare.defaultTimeToCompare.
The default value is 1h. The application searches for the iteration available within the range of one hour before current time. You can change the default value as per your requirement. Use one of the following types of units to specify a time value: seconds (s), minutes (m), hours (h), days (d). You can use only one type of unit to define the time value. Using a combination of units is not supported. Few examples of time values are listed:
1s
10m
12h
1d
For example, if you set the property as com.ptc.windchill.associativity.structure.compare.defaultTimeToCompare default=2d, the application compares the current iteration with the first iteration that was available within the range of two days or 48 hours before the current time.