[worldspace editorID].HeigthMap.[West cell].[South cell].[East cell].[North cell].[z black].[z white].[z min].[z max].dds

The min/max cell coordinates are the actual cells that contain terrain height data.
All z values are actual z values divided by 8.
z black/white are the lowest and highest possible z value your texture might represent, i.e. the z values of pure black and pure white pixels.
    Copy Skyrim worldspace values if your heightmap is generated by xLodGen.
z min/max corresponds to the actual lowest/highest point of the terrain. They are for optimization, but just use z black/white if you are not sure.

Example:

Tamriel.HeightMap.-57.-43.61.50.-32768.32768.-4629.4924.dds
native Skyrim.esm data

Terrain heightmap for Tamriel
Each cell has 32x32 heightmap data points, so max resolution is 32x32 pixels per cell.