Syntax options:

       TRANSACTION_DEFAULT=IMPLICIT
       TRANSACTION_DEFAULT=DISTRIBUTED
       NOTRANSACTION_DEFAULT

    Specifies when SQL starts a transaction and how SQL handles
    default distributed transactions. You can specify the following
    options:

    o  TRANSACTION_DEFAULT=IMPLICIT

       Causes SQL to start a transaction when you issue either a SET
       TRANSACTION statement or the first executable SQL statement in
       a session.

    o  TRANSACTION_DEFAULT=DISTRIBUTED

       Causes SQL to use the distributed transaction identifier (TID)
       for the default distributed transaction established by the
       DECdtm system service SYS$START_TRANS. Using this option
       eliminates the need to declare context structures in host
       language programs and to pass context structures to SQL module
       procedures. Because it closes all cursors, it also eliminates
       the need to call the SQL_CLOSE_CURSORS routine.

       You must explicitly call the DECdtm system services when you
       use this option.

       This option provides support for the Structured Transaction
       Definition Language (STDL) of the Multivendor Integration
       Architecture (MIA) standard.

       If you specify the TRANSACTION_DEFAULT=DISTRIBUTED option with
       the CONTEXT qualifier, you must declare a context structure
       and pass the context structure to the statements named in
       the CONTEXT qualifier or, if you specify CONTEXT=ALL, to most
       executable statements involved in the distributed transaction.
       See the Oracle Rdb SQL Reference Manual for information
       about which executable statements do not require a context
       structure.

    o  NOTRANSACTION_DEFAULT

       Prevents SQL from starting a transaction unless you execute
       a SET TRANSACTION statement. If you use this qualifier and
       issue an executable statement without first issuing a SET
       TRANSACTION statement, SQL returns an error.

    The default is TRANSACTION_DEFAULT=IMPLICIT.