Persistent fields (in the java sense) of a Node are attributes. Basically, all fields that are NOT static, const nor transient are attributes. The persistence management of the Node require each attribute to have accessors, which are declared in the node.

Attribute accessors are the methods to get and set the attribute value. The accessors of a Node are automatically resolved by the compiler with the syntax:

Sphere s; // has an attribute diameter
s[diameter] = 5; // automatically resolve the setter
float d = s[diameter]; // automatically resolve the getter