outstanding transaction in AXI4 protocol

In AXI4 we don't have write data interleaving, so if your master is issuing multiple write transactions using different IDs, there is a strict ordering requirement that all the WDATA transfers for the first issued AW channel transfer must be completed before any of the WDATA transfers for the second issued AW channel transfer.

However the slave(s) being accessed could respond with B channel responses in a different order, so if the target slave(s) can respond to the second transaction before the first, they can do so, knowing that the master will know which transfer this B channel response refers to (because each transaction would have a different ID).

If the master has used the same ID for both transactions, the B channel responses must come back to the master in the same order they were issued by the master.

In AXI4 we don't have write data interleaving, so if your master is issuing multiple write transactions using different IDs, there is a strict ordering requirement that all the WDATA transfers for the first issued AW channel transfer must be completed before any of the WDATA transfers for the second issued AW channel transfer.

However the slave(s) being accessed could respond with B channel responses in a different order, so if the target slave(s) can respond to the second transaction before the first, they can do so, knowing that the master will know which transfer this B channel response refers to (because each transaction would have a different ID).

If the master has used the same ID for both transactions, the B channel responses must come back to the master in the same order they were issued by the master.