Advanced Customization > Business Logic Customization > Data Exchange using Standards in Windchill > STEP Data Exchange using EXPRESS > STEP Foundation > EXPRESS Customizations > Advanced Customization — Implementing Post and Pre Converters
  
Advanced Customization — Implementing Post and Pre Converters
When to Write Pre or Post Converters
When you need to override behavior before the conversion or after the conversion.
When you need to modify the source and target model before or after, the conversion from one format to another.
Doing this can be considered as data tuning.
Extend wt.ixb.step.STEPConverter interface
Source model and target model are passed to pre and post converters APIs.
Implementation of the interface can change the models that are used in converters.
Use EDM SDK APIs to change the source model and target model.
For more information on APIs, see the EDMassist website.
Adding the service.properties entry for the delegate
In IXDocumentDelegateSTEP-service.properties.xconf :
<Service context="default" name="="wt.ixb.step.STEPConverter">

<Option serviceClass=“<your implementation>" requestor="= "java.lang.Object"

 selector=“<selector name>" cardinality="duplicate"/>

</Service>
Update the following property in stepdex.xconf to change converter selector: wt.stepdex.converter.selector=<selector>