XMI Export of Sequence Diagrams/Combinded Fragment

[uml_2005]

Hi,

i am using UML 2.0 features like combined fragments (loops, alternatives, and so on) in sequence diagrams.
A simple examlple:
2 actors who exchange a message and this message should be exchanged until a condition ist true.

When i draw this example by using combined fragments (loop) and then export the sequence diagram in a XMI file, i can not finde the connection between the message and the loop.

Is there any information in the XMI file which can tell me which message is contained in a combined fragment?

Thanks for helping...