Border points
The capacity to be auctioned comprises not only available technical capacity but also includes capacity that shippers wish to offer on PRISMA under the Surrender of Capacity measures.
As part of the Congestion Management Procedures (CMP), GTS can offer Oversubscription & Buy Back (OBB) capacity at interconnection points (including virtual IPs) where there is contractual congestion.
The basic principle is that all available capacity at the interconnection points (including virtual IPs) is auctioned as bundled capacity. Based on the capacity offered by the TSOs, PRISMA determines how much capacity is offered as bundled capacity. If one TSO has offered more capacity than the other, this ‘extra’ capacity will be offered by PRISMA as unbundled.
GTS offers interruptible capacity if all firm capacity at an interconnection point (or virtual IP) is sold out. Interruptible capacity is offered at auction only as a DA capacity product.
For operational arrangements see NC Interoperability