The reason you're seeing 100-199 I think is the Fexes on Module 1 are 100-199, Module 2 are 200-299, and so on.
I have the same problem: racks in our data center are 0201, 0202, 0301, 0302, etc. My proposed solution is make the Fex numbers 6 or 7 digit, or allow for names to be used rather than numbers.