The CUP issues the dc_trn_begin_s function to start a transaction.

The range of a global transaction is from issuing the dc_trn_begin_s function to acquisition of a synchronous point (commit).

Once the dc_trn_begin_s function has been issued, another issuance of that function is unavailable within the global transaction.

If an RPC is executed from the CUP to an SPP, the CUP becomes a route transaction branch and the SPP a transaction branch.

The following figure shows the relation between transactions and RPCs.

Figure 2-9 Relationship between transactions and RPCs