SVD2006 height - EPSG:20000

WKT

VERTCS["SVD2006_height", 
	VDATUM["Svalbard_vertical_datum_2006"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["SVD2006_height", 
	VDATUM["Svalbard_vertical_datum_2006"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "20000"]]

Data from @esri/proj-codes

{
  "wkid": 20000,
  "latestWkid": 20000,
  "macro": "PE_VCS_SVD2006_HEIGHT",
  "name": "SVD2006_height",
  "wkt": "VERTCS[\"SVD2006_height\",VDATUM[\"Svalbard_vertical_datum_2006\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"SVD2006_height\",VDATUM[\"Svalbard_vertical_datum_2006\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"20000\"]]",
  "description": "SVD2006 height",
  "authority": "EPSG",
  "version": "10.063(13.1.0)",
  "deprecated": "no",
  "areaname": "Arctic - 81~10'N to 76~10'N, 4~W to 38~E",
  "extent": {
    "slat": 76.16,
    "nlat": 81.17,
    "llon": -3.35,
    "rlon": 38.01
  }
}