There is a line of anerythristic sand boas -- 'Holloway reduced pattern', 'HRP' -- that is categorized in 'levels', but there isn't any decimal position. Each snake is ranked (1-10, IIRC) basically by amount of white color (and indirectly by price
).
Could you link someone talking about such a grading system, or put it in context (how is this used in a sentence, what species does it refer to, etc)?