EntityReference nodes may be used to represent an entity reference in the tree. Note that character references and references to predefined entities are considered to be expanded by the HTML or XML processor so that characters are represented by their Unicode equivalent rather than by an entity reference. Moreover, the XML processor may completely expand references to entities while building the Document, instead of providing EntityReference nodes. If it does provide such nodes, then for an EntityReference node that represents a reference to a known entity an Entity exists, and the subtree of the EntityReference node is a copy of the Entity node subtree. However, the latter may not be true when an entity contains an unbound namespace prefix. In such a case, because the namespace prefix resolution depends on where the entity reference is, the descendants of the EntityReference node may be bound to different namespace URIs. When an EntityReference node represents a reference to an unknown entity, the node has no children and its replacement value, when used by Attr.value for example, is empty.

As for Entity nodes, EntityReference nodes and all their descendants are readonly.

Note: EntityReference nodes may cause element content and attribute value normalization problems when, such as in XML 1.0 and XML Schema, the normalization is performed after entity reference are expanded.

See also the Document Object Model (DOM) Level 3 Core Specification.