See volumes for an explanation of standard volumes and OpenVDB volumes.
This node iteratively adjusts the voxel values to properly respect the distance to the zero crossing line. This requires proper signed distance fields for the results to be meaningful.
If you have significant departures from a proper signed distance field, you can rebuild it with the VDB From Polygons node. That node will implicitly convert an input SDF to polygons, then convert the polygons back to an SDF.
The name(s) of the VDB volume primitives in the input to be normalized. See specifying volumes.
The number of rounds of renormalization that should be performed. More rounds are slower but will result in a more correct SDF.
The method for smoothing the SDF after each iteration. Later options in the list are slower but more accurate.