For example, each Sphere node might have a different radius, and different texture maps nodes will certainly contain different images to use as the texture maps. These parameters are called Fields. A node can have 0 or more fields. A name to identify this node. Nodes do not have to be named, but if they are named, they can have only one name.
Object hierarchy is implemented by allowing some types of nodes to contain other nodes.
Parent nodes traverse their children in order during rendering. Nodes that may have children are referred to as group nodes. Group nodes can have zero or more children. Node names must not begin with a digit, and must not contain spaces or control characters, single or double quote characters, backslashes, curly braces, the plus character or the period character. Info nodes should be used for persistent information like copyrights or author information.