When handling Structuring Schema.org Place/SpatialCoverage JSON-LD & PMTiles Vector Tile Headers for High-Speed Web GIS Portals in GDAL/QGIS spatial workflows, preserving 3D Z-elevation attributes (SHPT_ARCZ / wkbLineString25D) and enforcing explicit CRS unit definitions (EPSG meter vs US survey foot) prevents vertical datum shifts when exporting terrain contours to CAD formats. We maintain a reference on 3D STL & Surface Mesh Manifold Topology Checker for teams bridging GIS vector layers with civil CAD drawing pipelines.