nsIExtendedExpatSink in Firefox 3.6a1pre

 Called when a prefix mapping is no longer in-scope, after any
 endElement events.
 @param aPrefix The prefix that was being mapped. This is the empty string
                when a default mapping scope ends.

 This is called for a declaration of notation.  The base argument is
 whatever was set by XML_SetBase. aNotationName will never be
 null. The other arguments can be.
 @param aNotationName The notation name.
 @param aSysId The notation's system identifier, or null if none was given.
 @param aPubId The notation's pubilc identifier, or null if none was given.

 Called at the beginning of the DTD, before any entity or notation
 events.
 @param aDoctypeName The document type name.
 @param aSysid The declared system identifier for the external DTD subset,
               or null if none was declared.
 @param aPubid The declared public identifier for the external DTD subset,
               or null if none was declared.

 Called when a prefix mapping starts to be in-scope, before any
 startElement events.
 @param aPrefix The Namespace prefix being declared. An empty string
                is used for the default element namespace, which has
                no prefix.
 @param aUri The Namespace URI the prefix is mapped to.

 This is called for a declaration of an unparsed (NDATA) entity.
 aName, aSysid and aNotationName arguments will never be
 null. The other arguments may be.
 @param aName  The unparsed entity's name.
 @param aSysId The notation's system identifier.
 @param aPubId The notation's pubilc identifier, or null if none was given.
 @param aNotationName The name of the associated notation.