A distributed transaction is a transaction that uses more than
    one database handle. Examples of a distributed transaction
    include:

    o  a transaction that attaches more than once to a single Oracle Rdb
       database

    o  a transaction that attaches to two or more Oracle Rdb databases

    o  a transaction that attaches to more than one database
       management system (an Oracle Rdb database and a Oracle CODASYL
       DBMS database, for example)

    Distributed transactions are managed by the DECdtm services.
    DECdtm services assigns a unique distributed transaction
    identifier (distributed TID) to each distributed transaction
    when the distributed transaction is started.

    Use the DISTRIBUTED_TRANSACTION keyword by itself (without the
    DISTRIBUTED_TID distributed-tid clause) when you want to start a
    distributed transaction.

    For complete information on distributed transactions, see the
    Oracle Rdb Guide to Distributed Transactions.