Fair Isle - EPSG:5741

WKT

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

WKT2

VERTCRS["Fair_Isle", 
	VDATUM["Fair_Isle"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5741"]]

Data from @esri/proj-codes

{
  "wkid": 5741,
  "latestWkid": 5741,
  "macro": "PE_VCS_FAIR_ISLE",
  "name": "Fair_Isle",
  "wkt": "VERTCS[\"Fair_Isle\",VDATUM[\"Fair_Isle\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"Fair_Isle\",VDATUM[\"Fair_Isle\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5741\"]]",
  "description": "Fair Isle",
  "authority": "EPSG",
  "version": "6.15(9.3.0.0)",
  "deprecated": "no",
  "areaname": "UK - Fair Isle onshore",
  "extent": {
    "slat": 59.45,
    "nlat": 59.6,
    "llon": -1.76,
    "rlon": -1.5
  }
}