This interface represents a notation declared in the DTD. A notation either
declares, by name, the format of an unparsed entity (see section 4.7 of
the XML 1.0 specification ), or is used for formal declaration of
processing instruction targets (see section 2.6 of the XML 1.0
specification ). The nodeName attribute inherited from
Node is set to the declared name of the notation.
The DOM Level 1 does not support editing Notation nodes;
they are therefore readonly.