In the gas industry a standard unit of measure is required. In the English system it is the standard cubic foot. In the metric, it
is the standard cubic meter. This standard unit is the basis of all exchange in the gas industry. When the unit of purchase is
the energy content (BTU) we achieve it by multiplying the BTU content of a standard cubic foot times the number of cubic
feet delivered to the customer. So we must obtain standard cubic feet or meters.