N2000 height - EPSG:3900

WKT

VERTCS["N2000_height", 
	VDATUM["N2000"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["N2000_height", 
	VDATUM["N2000"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "3900"]]

Data from @esri/proj-codes

{
  "wkid": 3900,
  "latestWkid": 3900,
  "macro": "PE_VCS_N2000",
  "name": "N2000_height",
  "wkt": "VERTCS[\"N2000_height\",VDATUM[\"N2000\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"N2000_height\",VDATUM[\"N2000\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"3900\"]]",
  "description": "N2000 height",
  "authority": "EPSG",
  "version": "7.5.1(10.1.0)",
  "deprecated": "no",
  "areaname": "Finland - onshore",
  "extent": {
    "slat": 59.75,
    "nlat": 70.09,
    "llon": 19.24,
    "rlon": 31.59
  }
}