How to use XA transactions on UM?

Hi,

What is impact of setting xa=true on
com.pcbsys.nirvana.client.nTransactionFactory.create(nTransactionAttributes attr, boolean xa)

as opposed to using the plain create method
com.pcbsys.nirvana.client.nTransactionFactory.create(nTransactionAttributes attr)?

Does anyone knows why to the C++ and C# API do not have the xa create method?

Best Regards,