Reserve provisions to other nodes
I believe
// Reserve provisions to another nodes via transfer links
+ sum(gn2n_directional(grid, node, node_)${restypeDirectionNodeNode(restype, up_down, node_, node)},
should be
// Reserve provisions to another nodes via transfer links
+ sum(gn2n_directional(grid, node, node_)${restypeDirectionNodeNode(restype, up_down, node, node_)},