XOpen DTP State Machine

XA STandard is well known in the industry, however it's difficult to find proper state machine diagram. It's here.

Does ORA-02049 invalidate DBMS XA transaction?

There is a widely spread rule in WebLogic/Oracle XA processing environment to keep DISTRIBUTED_LOCK_TIMEOUT on a very high level, higher than JTA Timeout and XA Timeout to avoid XA consistency problems. In my opinion it's not a valid configuration, creating unnecessary delays in processing data locks. 
This exercise shows that on a database level, lock timeout, manifested by 'ORA-02049: timeout: distributed transaction waiting for lock', does not change transactional state of the work i.e. rolls back the transaction.