rg/sax/features/namespaces feature is
true (the default).
There are cases, however, when applications need to use prefixes in character data or in attribute values, where they cannot safely be expanded automatically; the start/endPrefixMapping event supplies the information to the application to expand prefixes in those contexts itself, if necessary.
Note that start/endPrefixMapping events are not guaranteed to be properly nested relative to each other: all startPrefixMapping events will occur immediately before the corresponding {@link #startElement startElement} event, and all {@link #endPrefixMapping endPrefixMapping}events will occur immediately after the corresponding {@link #endElement endElement} event,but their order is not otherwise guaranteed.
There should never be start/endPrefixMapping events for the "xml" prefix, since it is predeclared and immutable.
@param prefix the Namespace prefix being declared.An empty string is used for the default element namespace, which has no prefix.
@param uri the Namespace URI the prefix is mapped to
@throws org.xml.sax.SAXException the client may throwan exception during processing
@see #endPrefixMapping
@see #startElement