To my eye, nothing at all, it conforms to type. 
 
I've seen more than a few of these, they all vary slightly, but overall form is the same.  
 
Here is one I have, it was bought in Australia during the 1920's, but supposedly came from Malang in East Jawa during the period 1850-1900. 
 
My info from Jawa during 1980's is that it is North Coast Jawa.
		 
		
		
		
			
		
		
		
		
		
		
		
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