1.3.1.2 Transaction Recovery
The atomicity property of a transaction guarantees that all participants in the transaction receive the same outcome. To honor this guarantee, transaction managers have to be capable of recovering from transient failures.
After a transient failure, the transaction manager re-establishes connectivity with the local LU, if the connection with the local LU is lost, and participates in the re-establishment of consistent state at the local and remote LUs.
The following sequence diagram is a schematic of the interactions that take place between Sync Point Services (SPS) in a remote LU, a local LU, SPS in a local LU, and a transaction program during recovery initiated by a remote LU.

Figure 3: MS-DTCLU recovery
All the exchanges depicted are notional, and are not intended to provide an accurate representation of any concrete protocol. The protocols involved are specified as follows:
The protocol between Local LU.SPS and the transaction manager is specified in sections 1.3.2.2.1 and 3.3.
The protocol between the Local LU.SPS and the Remote LU.SPS is specified in [IBM-LU62Guide].
The intent of these interactions is similar to that of the recovery protocol between a subordinate transaction manager and a superior transaction manager as specified in [MS-DTCO]. However, the role played by Local LU.SPS does not correspond exactly with any of the roles as specified in [MS-DTCO]. Consequently, this document specifies an additional role, LU 6.2 Implementation, in section 1.3.2.1.