HVD height - ESRI:105601

WKT

VERTCS["HVD_height", 
	VDATUM["Hellenic_Vertical_Datum"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["HVD_height", 
	VDATUM["Hellenic_Vertical_Datum"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["Esri", "105601"]]

Data from @esri/proj-codes

{
  "wkid": 105601,
  "latestWkid": 105601,
  "macro": "PE_VCS_HVD_HT",
  "name": "HVD_height",
  "wkt": "VERTCS[\"HVD_height\",VDATUM[\"Hellenic_Vertical_Datum\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"HVD_height\",VDATUM[\"Hellenic_Vertical_Datum\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"Esri\",\"105601\"]]",
  "description": "HVD height",
  "authority": "Esri",
  "version": "13.5.0",
  "deprecated": "no",
  "areaname": "Greece",
  "extent": {
    "slat": 33.26,
    "nlat": 41.75,
    "llon": 18.26,
    "rlon": 30.23
  }
}