NAVD88 height (Intl Feet) - EPSG:8228

WKT

VERTCS["NAVD88_height_(ftIntl)", 
	VDATUM["North_American_Vertical_Datum_1988"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Foot", 0.3048]]

WKT2

VERTCRS["NAVD88_height_(ftIntl)", 
	VDATUM["North_American_Vertical_Datum_1988"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Foot", 0.3048]], 
	ID["EPSG", "8228"]]

Data from @esri/proj-codes

{
  "wkid": 8228,
  "latestWkid": 8228,
  "macro": "PE_VCS_NAVD88_HT_IFT",
  "name": "NAVD88_height_(ftIntl)",
  "wkt": "VERTCS[\"NAVD88_height_(ftIntl)\",VDATUM[\"North_American_Vertical_Datum_1988\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Foot\",0.3048]]",
  "wkt2": "VERTCRS[\"NAVD88_height_(ftIntl)\",VDATUM[\"North_American_Vertical_Datum_1988\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Foot\",0.3048]],ID[\"EPSG\",\"8228\"]]",
  "description": "NAVD88 height (Intl Feet)",
  "authority": "EPSG",
  "version": "9.2(10.8.0)",
  "deprecated": "no",
  "areaname": "USA - onshore - AZ MI MT ND OR SC",
  "extent": {
    "slat": 31.33,
    "nlat": 49.01,
    "llon": -124.6,
    "rlon": -78.52
  }
}