Connection – Process that creates the physical connection between the distribution or transport network and the gas delivery point at the consumption site.

Thermal year – Standard reference period for supplying gas, running from October 1st to September 30th of the following year.

Decompression cabin – Plant that connects gas pipelines at different pressures and lowers the gas pressure to bring it into line with the usage needs of the end consumer.

Eligible client – Client who, according to law, may freely choose their supplier of electricity or natural gas. For natural gas, from January 1st 2003 onwards all consumers are eligible clients.

Dispatching – The coordinated management and control of the extraction plants and storage, of the transport network and of the distribution network, as well as of the accessory services. Dispatching is conducted using special equipment for the purpose.

Distribution – The transportation of natural gas through local gas pipeline networks for delivery to the customers.

Downstream – All activities that take place between loading the gas at the export terminals (or injecting it into extra-high pressure gas pipelines) and its use by the end consumers. Downstream activities include transport over sea (or land), distribution and sales.

LNG (Liquefied Natural Gas) – Light hydrocarbon made up predominantly of methane, converted to liquid state using atmospheric pressure and a temperature of -161C° (it is subjected to a process of regasification at the time of use). Easily transportable, LNG is used mostly as a combustible gas and as a vehicle fuel.

Gas pipeline – Conduit for transporting gas at high pressure over long distances.

M – The coefficient to adapt to the altitude and climate factors of clients in the regulated market who have volumetric metering systems that meter gas at low pressure and which are not fitted with correctors.

Standard cubic metre (Sm³) – Unit of measurement for calculating the volume of gas, used under determined conditions defined as "standard", i.e. at atmospheric pressure and at a temperature of 15°C.
Normal cubic metre (Nm³) – Unit of measurement used for gas under "normal" conditions, i.e. at atmospheric pressure and at a temperature of 0°C. This is also used for measuring liquid gas (LNG). The ratio of the normal cubic metre to the standard cubic metre is 1 Nm³ = 1.056 Sm³.

Higher Heating Value (HHV) – This is the quantity of heat, expressed in joules [J], that is liberated by the complete combustion of 1 standard cubic metre of dry gas at a temperature of 15°C and at an absolute pressure of 1.01325 bar, with excess air at the same temperature and pressure as the gas, when the products of its combustion are brought back to the starting temperature of the gas and the water formed (which exists as a vapour during combustion) is brought back to the liquid state, also at the starting temperature of the gas.

Storage – Gas reserve stored on terrain with specific geological characteristics, preferably sited near zones of high consumption.

Transport – The transport of natural gas through the gas pipeline network, excluding extraction pipelines and distribution networks.

Upstream – Activities involved in exploration, production and delivery to an export terminal.

Transportation – Service for transporting gas from one point to another on the network, operated by the distributor of the network at the request of the owner of the gas.