“12.0.6” Indicates that the price of gas is indexed to the average price of an assortment of oil products over the previous 12 months, that there is an interval of 0 months between the end of the 12 month period and the introduction of its average price into the formula and that the price obtained through this formula will be applied to the gas contract for the next 6 months.

So “3.3.1” means that the price is indexed to the average price of oil over previous 3 months and that there is an interval of 3 months between the end of the 3 months period and the introduction of the average price into the formula and that the price obtained through this formula will be applied to the gas contract for the next month