Additonal improvement on MSDTC enlistment.
You can specify 3 diffrent behaviors using the xaopt connection string option.

In any case XARMcreate() lets MSDTC process invoke xa_open() in pgxalib.dll. in MSDTC process upon successful link.

 1: The current default behavior.
 2: Same as above except it simply examines if the recovery for the specified
    datasource is available before calling XARMcreate().
 3: 2. + xa_open() tries to connect to the specified datasource as Network
    Service user.