This interface is a generic one that is
extended by Text, CDATASection
(which extends Text) and
Comment. Any node in a document tree that
implements CharacterData also implements one of
these more specific types. This interface exists simply to group the
string manipulation methods that these text-related node types all
share.
The CharacterData interface defines a mutable
string. geTData( ) returns the
"character data" as a
String object, and setData( )
allows it to be set from a String object.
getLength( ) returns the number of characters of
character data, and substringData( ) returns just
the specified portion of the data as a string. The
appendData( ), deleteData( ),
insertData( ), and replaceData(
) methods mutate the data by appending a string to the end,
deleting region, inserting a string at the specified location, and
replacing a region with a specified string.

public interface CharacterData extends Node {
// Public Instance Methods
void appendData(String arg) throws DOMException;
void deleteData(int offset, int count) throws DOMException;
String getData( ) throws DOMException;
int getLength( );
void insertData(int offset, String arg) throws DOMException;
void replaceData(int offset, int count, String arg) throws DOMException;
void setData(String data) throws DOMException;
String substringData(int offset, int count) throws DOMException;
}