Here is a link to Zoo Med's instructions for interpreting the readings. It's the same exact meter, just with Zoo Med stickers. It has information on the Ferguson scale. There used to be a Yahoo group on UVB meters, but I don't know if it still exists or not.
Hands down, this is the best website for information about the Solarmeter and its readings. There is a ton of information so you might find yourself reading it multiple times until everything starts to sink in
Those numbers would be great if they had the 6.2 version, but they have the 6.5 which gives the reading in UV index instead. Very interesting article, I'm glad you posted it.
I was in a hurry and I've been meaning to research this more myself, so I posted that link in haste. Good job pointing out that we are discussing a different meter. I have the zoomed one.
I think I recall the resign to shoot for was 50, but my memory is foggy as to where I obtained that.
Shoot a Todd @ lightyourreptiles.com an email and he will have your answer and possible links to the information!