The third row is devoted to bill/payment mail that is part of the NHH-to-NHH (Non-household-to-Non-household) sector.
The third row is devoted to correspondence between households.
mnli hypothesis: The third row is devoted to correspondence between households. premise: The third row is devoted to bill/payment mail that is part of the NHH-to-NHH (Non-household-to-Non-household) sector.