Several classes of functions are shown to be Donsker by an argument
based on partitioning the sample space. One example is the class of all
nondecreasing functions $f: \mathbb{R} \to \mathbb{R}$ such that $0 \leq f \leq
F$ for a given function F with $\int F^2 dP/ \sqrt{1-P} <
\infty$.