The number attribute of a distribution target in Windchill is often just a numeric value, and may thus not carry any useful information on the destination ERP system that the data should eventually be published to. Thus, when using closed loop transactions, there is a need to customize Windchill ESI services to fetch a value for the Destination parameter that represents the destination ERP system as appropriate. See the ERP Connector Customizer's Guide for more information on how Windchill ESI services may be customized to send a custom value for the <Destination> element in the Windchill ESI response.