EMA C++ Configuration Guide : 3 Configuration Groups : 3.2 IProvider Group : 3.2.2 Setting a Default IProvider
 
3.2.2 Setting a Default IProvider
If a DefaultIProvider is not specified, then the Enterprise Message API uses the first IProvider component in the IProviderGroup. However, you can specify a default provider by including the following parameter on a unique line inside the IProviderGroup but outside the IProviderList.
 
 
<DefaultIProvider value="VALUE"/>