def define_dynamic_lists(mod):
    """
    Zone_Power_Injections and Zone_Power_Withdrawals are lists of
    components that contribute to load-zone level power balance equations.
    sum(Zone_Power_Injections[z,t]) == sum(Zone_Power_Withdrawals[z,t])
        for all z,t
    Other modules may append to either list, as long as the components they
    add are indexed by [zone, timepoint] and have units of MW. Other modules
    often include Expressions to summarize decision variables on a zonal basis.
    """
    mod.Zone_Power_Injections = []
    mod.Zone_Power_Withdrawals = []
