def max_transmit_rule(mod, l, tmp):
    """
    **Constraint Name**: TxSimple_Max_Transmit_Constraint
    **Enforced Over**: TX_SIMPLE_OPR_TMPS

    Transmitted power cannot exceed the maximum transmission flow capacity in
    each operational timepoint.
    """
    return (
        mod.TxSimple_Transmit_Power_MW[l, tmp]
        <= mod.Tx_Max_Capacity_MW[l, mod.period[tmp]]
        * mod.Tx_Availability_Derate[l, tmp]
    )