RH70 - EPSG:5718

WKT

VERTCS["RH70", 
	VDATUM["Rikets_Hojdsystem_1970"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["RH70", 
	VDATUM["Rikets_Hojdsystem_1970"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5718"]]

Data from @esri/proj-codes

{
  "wkid": 5718,
  "latestWkid": 5718,
  "macro": "PE_VCS_RH70",
  "name": "RH70",
  "wkt": "VERTCS[\"RH70\",VDATUM[\"Rikets_Hojdsystem_1970\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"RH70\",VDATUM[\"Rikets_Hojdsystem_1970\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5718\"]]",
  "description": "RH70",
  "authority": "EPSG",
  "version": "6.7(9.3.0.0)",
  "deprecated": "no",
  "areaname": "Sweden - onshore",
  "extent": {
    "slat": 55.28,
    "nlat": 69.07,
    "llon": 10.93,
    "rlon": 24.17
  }
}