This attribute is mainly used for exclusive accesses.
set_id() must set this attribute to the value passed as
argument. The method
get_id() must return the value of this attribute.
This attribute must be set by the master originating the transaction. The interconnect must modify this attribute to ensure its uniqueness across all its masters before passing the transaction to the addressed slave.
The default value of this attribute must be 0.
This attribute is specific to the AXI, ACE, and AHB buses. It is ignored for transactions modeling transfers on the APB bus.