The Fixed charge has been extended, so that you can specify a custom fixed charge quantity per meter account.
To enable this, you check the checkbox on the tariff line item edit screen with Fixed Charge selected, the checkbox to allow 'per meter account' quantities. You can then also specify any wierd 'unit' you like, for example 'toilets' for a tariff called 'Pan charge'.
To specify the quantity of toilets, you would then go to the meter account's edit screen, where you normally specify the meters and tariffs, and then you'll see there is a new (3rd) block below where you can specify meter account specific tariff parameters, and there you can then fill in the number of toilets for that customer. This quantity will then be used to multiply with the rate as defined in that particular tariff screen, to get the amount to charge.
In the case of rates where accounts fall into different 'categories', e.g. distance from Germiston in the case of some Eskom tariffs, where the total rates charged can possibly not be multiplied with a quantity to get an amount, one can enter each option or category as a separate customer fixed charge item, and enter 0 or 1 in the edit meter account screen, depending on whether the particular tariff item applies or not.