According to the CRE deliberation of 26 October 2017 for the Trading Region France, maintenance works on the Teréga and GRTGaz networks are expressed as restrictions according to the following rules:
if the work affects one point in particular, the capacity restriction is related to the corresponding point;
if the work is located on GRTgaz’s northern network (limits N1, N2, N3, NS1 described in paragraph 2.3.4), the restriction is related to the superpoints upstream of the limit;
if the work is located on GRTgaz’s southern network or Terega’s network (limits NS2, NS3, NS4, S1 described in paragraph 2.3.4), the restriction is related to the superpoints downstream of the corresponding limits unless the exit capacities of the superpoints are insufficient to accept the restriction rates. In this case, the rates will be applied on the upstream superpoint.
These types of reduction may be simultaneous.
You can see the limits in case of flows from North to South on the map below: