Within the competitive market paradigm, real time system operation has the responsibility not only of maintaining system reliability and security, but also of ensuring compliance to market protocols. This paper summarizes key areas where market protocols could impact real time system operation, with a focus on real-time market applications for generation-load balancing and congestion management. Constraint modeling, which is central to congestion management, is discussed further to highlight how it contributes to convergence between day-ahead scheduling and real-time dispatch.