 Transaction requests take place by calling interface functions of these channel models, which encapsulate low-level details of the information exchange.At the transaction level, the emphasis is more on the functionality of the data transfers – what data are transferred to and from what locations – and less on their actual implementation, that is, on the actual protocol used for data transfer.This approach makes it easier for the system-level designer to experiment, for example, with different bus architectures (all supporting a common abstract interface) without having to recode models that interact with any of the buses, provided these models interact with the bus through the common interface.