Playing with displacements in the /mat context and having some issues:

First, where do parameters get set when dropping vops into /mat sandbox?
When working with materials in a SHOP context, parameter VOPs add their parameter to the containing material node, the one “U” takes you to. In /mat there is no container SHOP or material, so no parent node to step up to, so where do the parameters go? Relatedly, where do you collect the controlling parameters when promoting them?

Second, the displacements break when collapsing the sandboxed /mat nodes into a material.
It is turning the smooth continuous displaced surface into one fractured into quads with gaps between them. I saw this addressed in a video that I cannot find now, something to do with the nodes added by Houdini during the collapse. I see those but changing them has no effect.

attached… before and after “collapse into material” render grabs of displaced surface.

Found the fix for the weirdness in the displacement render.

The displacement bound parameter in the autocreated Properties node loses its connection to values set in the principled shader. Just deleted the expression instead of editing the ch() values and entered a value by hand. Render is smooth again!

I am guessing that the answer to the first part is to collapse the ad hoc network into a Material or sub net to have a place for parameters to register.