XML EntityDecl
The EntityDecl element represents a general entity and is declared in the internal subset of the DTD.
The EntityDecl is a named element and has a single child element, which is of type EntityDeclValue.
An entity declaration of the form:
<!ENTITY bookTitle "User Guide">
has
an EntityDecl element of name bookTitle and a child element of type
EntityDeclValue with a string value of User Guide
.