The ITEM class is an abstract class that has two children (or specialisations): the ELEMENT class (leaf nodes with values) and the CLUSTER class (group). Using the term ITEM means that either an CLUSTER or ELEMENT is allowed.
The ITEM class is an abstract class that has two children (or specialisations): the ELEMENT class (leaf nodes with values) and the CLUSTER class (group). Using the term ITEM means that either an CLUSTER or ELEMENT is allowed.