A method of accessing program meta-data is disclosed. The method includes receiving a plurality of program meta-data virtual containers, at least one of the virtual containers comprising normalized program meta-data of programs having instances in a plurality of time windows, receiving an input indicating a selected time window, the input at least one of comprises and refers to a time-window identifier identifying the selected time window, and using the time-window identifier to filter the plurality of virtual containers, so as to obtain a subset of the program meta-data which corresponds to the selected time window. Related apparatus and methods are also disclosed.