Hello Houdini users. I am very new to Houdini and am curious if there is a master list of these “$PR” type hscript expressions. I have done a few tutorials that utilize them and I don't understand their function.

Thank you in advance.

There is no such list, because most of them (like $PR) are “local variables”, in that they only apply to specific paramaters on specific nodes, and many have parameter-specific meaning, so they're described on the help pages for those nodes. We're also trying to slowly phase them out from critical places over time, because they effectively make decent performance impossible.

That said, a list of global HScript expression variables can be found here: http://www.sidefx.com/docs/houdini/network/expressions.html#globals [www.sidefx.com] Global variables are less problematic than local variables.

Thank you very much for you descriptive and timely reply ndickson!

Cheers!