The Network Code on Capacity Allocation Mechanisms (CAM NC) harmonises how network users can use the gas transmission network to enter or exit a market, and how these capacity rights can be obtained. Different forms of standard capacity products exist: there are long-term (monthly, quarterly and yearly) and short-term (day and within-day) capacity contracts. The use of the transmission network can be unrestricted (firm capacity) or with restrictions (interruptible and conditional capacity products).
To facilitate moving gas across markets, transmission system operators allow the exit from one market area with the right to enter a neighbouring market area at the interconnection points. Virtual trading points in each market place facilitate the exchange of capacity rights, so that network users can easily transfer them.
A harmonised EU-wide auction scheme supports network users to buy capacity on capacity booking platforms. In addition to harmonising rules for existing capacity, the CAM NC provides a harmonised process to build incremental-capacity.
The Guidelines on Congestion Management Procedures (CMP GL) harmonise the approaches to identify and deal with contractual congestion. The presence of contractual congestion implies that some network users cannot get the capacity product of their choice and must rely on mitigating measures to access the market. Such measures are necessary to improve the efficient network usage and the overall market efficiency, and to avoid investment in physical capacity when contracted capacity remains unused. Congestion management is strongly connected to capacity allocation, both dealing with network access rights.
