Curiously, like many tomes that have a hell of a lot of work hidden behind a simple façade, it's actually quite interesting,
 
	when one is curious about 'how things wear out',  often involving denominations that have never appealed....
 
	Strange thing, grading.
 
	"Eye appeal" or "better in the hand" or "toning" etc. etc. could make all this a referenceless minefield,
 
	whereas this books is a good attempt to create a reference frame that's needed.