GLSL `projectionMatrix` and `modelViewMatrix`


I don’t understand the naming convention used in the Grasshopper GLSL component.
It seems that _worldToClip is the precompute matrix of the projection and model-view.
But where is projectionMatrix and modelViewMatrix ?
What does Clip define in uniform names?

Thank you in advance for your help. I’m not very good with GLSL so not seeing the current names completely confuses me …