ODN (Offshore) height - EPSG:7707

WKT

VERTCS["ODN_(Offshore)_(height)", 
	VDATUM["Ordnance_Datum_Newlyn_(Offshore)"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["ODN_(Offshore)_(height)", 
	VDATUM["Ordnance_Datum_Newlyn_(Offshore)"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "7707"]]

Data from @esri/proj-codes

{
  "wkid": 7707,
  "latestWkid": 7707,
  "macro": "PE_VCS_ODN_OFFSHORE_HT",
  "name": "ODN_(Offshore)_(height)",
  "wkt": "VERTCS[\"ODN_(Offshore)_(height)\",VDATUM[\"Ordnance_Datum_Newlyn_(Offshore)\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"ODN_(Offshore)_(height)\",VDATUM[\"Ordnance_Datum_Newlyn_(Offshore)\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"7707\"]]",
  "description": "ODN (Offshore) height",
  "authority": "EPSG",
  "version": "8.9.3(10.5.0)",
  "deprecated": "no",
  "areaname": "UK - offshore 49~45'N to 61~N, 9~W to 2~E",
  "extent": {
    "slat": 49.75,
    "nlat": 61.01,
    "llon": -9.01,
    "rlon": 2.01
  }
}