There are specific terms for the relationships between nodes in a tree. Each node IMMEDIATELY DOMINATES the next node below it, providing they are connected by a branch, and providing no other node intervenes. So P immediately dominates down, D immediately dominates this, and N immediately dominates road. No other node intervenes between P and down, and so on. The node PP immediately dominates the two nodes P and NP, and NP immediately dominates D and N: again, no other nodes intervene. A node that immediately dominates another node or set of nodes is their MOTHER: so, far example, PP is the mother of P and NP, and NP is the mother of D and N. It won't surprise you that P and NP are the DAUGHTERS of PP, and D and N are the daughters of NP. The lexical items down, this and road are the daughters of P, D and N respectively.