3.3.7.3 Begin Phase One
The Begin Phase One event MUST be signaled with the following arguments:
An Enlistment object
A Boolean value that indicates whether the Transaction Manager Communicating with an LU 6.2 Implementation Facet SHOULD or MUST NOT attempt to perform a Single Phase Commit (This argument is not used by this protocol and is ignored.)
If the Begin Phase One event is signaled, the Transaction Manager Communicating with an LU 6.2 Implementation Facet MUST perform the following actions:
If the connection state is Active:
Send a TXUSER_DTCLURMENLISTMENT_MTAG_TO_LU_PREPARE message using the connection referenced by the provided Enlistment object.
Set the connection state to Awaiting Prepare Response.
Otherwise, ignore the event.