What Do The Numbers Mean On Excavators?

What Do The Numbers Mean On Excavators? 3 stands for excavator (product type), 20 stands for 20ton (tonnage), D represents D series, D is newer machine compare with B,C. If L is after series letter, example CAT320DL, L stands for long truck excavator. What are the sizes of Cat excavators? Small excavators: 11-19 tons. Medium