Principle of modifying multi-period load data in MOST?

[tanzhongtan]

Hi! I have just started using Matpower recently to simulate the dispatchable load. However, I don't quite understand the principle of modifying multi-period load data in MOST. In the given example of the manual, the load is at bus 3, set as a negtive generator. The time-varying load is set at CT_LOAD_ALL_PQ bus. However, there is no CT_LOAD_ALL_PQ bus in the casefile 'ex_case3b'. So, on which bus(es) are the demand data is changed in different period? Furthermore, I've checked the MOST function. It seems the power demand is always 0 at every bus at each tstep. How 'flow constraints' is built? Can anyone please help me?