Terminology used to describe the various elements of a street network:
A link consists of several connected vertices (2 or more, blue squares on the map below). The first vertex of a link is called the start-node / from-node and the last vertex is called the end-node / to-node.
Most of the nodes share coordinates with nodes of other links. The number of links sharing a node is referred to as the valency of the node. You should normally never reach more than 10. See also function Valency.
A node is also called an intersection - even if the valency is 1 or 2. A link where one of the nodes has valency 1 is called a dangling link. A node with valency 2 is called a pseudo-node. The red node on the map is such a pseudo-node.
A link is identified by it's ID (Magenta text on the map: 1, 2, 3 ....), which corresponds to the record ID's of the input dataset used by function NWcreate.
A node is identified by it's ID (Black text on the map: 1, 2, 3 ....). Node ID's are primarily ordered by valency in descending order and secondarily by x-coordinate in ascending order. Node ID's are assigned during network creation and can not be controlled by the user.
A location is a position on a link: e.g. 50% along link 70 - counted in the same direction as that the link has been digitized in. This app. matches the cursor on the map below. Locations are used when doing dynamic routing. The percentage needs to be strictly between 0 and 1.
