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.