Whats the difference between Light yellow filter #3 and #6

[StigHagen]

Im going to buy a light yellow filter for my lee system and found Lee has a #3 filter, though other systems have #6 for light yellow. What is the difference those two? Is #3 even lighter than #6?

 

[Ikon]

Yes it is. #3 is the lightest, #6 is the "darkest" of the light yellow filters.