This pattern node is a utility node for assisting in conversion of Cycle's Principled BSDF to an equivalent Lama Shading Network. For more information on the input parameters to Cycle's Principled BSDF, see the Blender documentation.

It is not expected users will manually create this node. However, the below images shows examples of how to wire PxrBlenderPrincipledInputs into a Lama network, that will create similar look to the Cycle's Principled BSDF.