In the following paragraphs, the methology and procedure for calculating technical capacity at entry and exit points are described. Topological information about the network is of particular significance.

Topological information about the network is important for calculating technical capacity at entry and exit points. Firstly, this such calculations include the nominal diameter, length and roughness of a pipe in a certain section of pipeline. Next, the capacity parameters of the stations where the pipeline sections are connected to each other or at which gas is injected or withdrawn (especially the injection and off-take pressure technically possible, the technical capacity of the gas pressure control system and, if necessary the topological information of the adjacent network) are significant. In addition to this, the gas composition parameters at the stations where gas is injected must be considered.

In order to be able to calculate the technical capacity at all entry and exit points once a year, it is important to consider as many load flow scenarios in one´s own network and in the whole market area as possible. In the load flow scenarios, the already marketed capacities at the entry and exit points as well as the maximum reservable firm exit capacity for distributor system operators – within the framework of internal orders – must be considered as well as estimations of future trader behaviour.

At an entry or exit point, technical capacity can be designated and marketed on a firm basis if the above-mentioned boundary conditions are not violated. Insofar as the boundary conditions mentioned above are partially not met, it is necessary to reduce the technical capacity on a firm basis at a suitable place (that means at an entry or exit point).

Should changes to the general technical conditions of the network arise during the year, in particular disconnection of an existing network connection, installation of a new network connection, additional technical capacity at an existing network connection), the process of calculating capacity – insofar as needed – will be repeated according to the new network topology.