Hon Dau 1992 - EPSG:5727

WKT

VERTCS["Hon_Dau_1992", 
	VDATUM["Hon_Dau_1992"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["Hon_Dau_1992", 
	VDATUM["Hon_Dau_1992"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5727"]]

Data from @esri/proj-codes

{
  "wkid": 5727,
  "latestWkid": 5727,
  "macro": "PE_VCS_HON_DAU_1992",
  "name": "Hon_Dau_1992",
  "wkt": "VERTCS[\"Hon_Dau_1992\",VDATUM[\"Hon_Dau_1992\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"Hon_Dau_1992\",VDATUM[\"Hon_Dau_1992\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5727\"]]",
  "description": "Hon Dau 1992",
  "authority": "EPSG",
  "version": "6.15(9.3.0.0)",
  "deprecated": "no",
  "areaname": "Vietnam - mainland",
  "extent": {
    "slat": 8.33,
    "nlat": 23.4,
    "llon": 102.14,
    "rlon": 109.53
  }
}