For this design, the KEEL "web service" is accumulating the values from 3 S-shaped curves: one for Lost Packets, one for Latency, and one for Bandwidth. The curves themselves are configured with the other parameters.
The most effective, perhaps the only cost effective way, to review the design is by understanding, and interacting with the design within the KEEL Toolkit where you can create multi-dimensional curve drawings to understand the interaction between the different curves.