From https://personal.math.ubc.ca/~CLP/about/ :

> For various reasons we have christened these notes “CLP” - none of those reasons can be found [here](https://en.m.wikipedia.org/wiki/CLP)

Presumably it's an inside joke or something.

Yeah no idea what it is, so I asked copilot, and it says CLP stands for Calculus Learning Project. Makes sense but don’t know if it is accurate :)