Specific random range in particle subUV?

I have a large texture for my particles in cascade and am trying to figure out how to have an initial random subUV in a specific range and have no blending or changes.

I’ve only figured out how to do completely random subUVs or subUVs in a range but they constantly change within that range. I am not entirely sure how the required suvUV section and subUV index module work together.