Scratch For Robots commands

I saw your basic Scratch For Robots commands for the PivotPi here. Where can I find more commands? I see the project for the snowman seems pretty advanced and I would like to understand and explore.

the commands that are related to PivotPi are here:

The rest of the snowman project is standard Scratch. Also the music uses SonicPi and runs in parallel, if I remember correctly.