O que é Financial transmission right?

A financial transmission right (FTR) from node $A$ to node $B$ entitles its holder, for each hour of its term, to a quantity times the day-ahead congestion price at $B$ minus that at $A$: a payment when the path is congested in the direction of the right, and, for an obligation, a charge when it is congested the other way. It is sold by the grid operator in auctions and funded by the congestion rents it collects.