NAD 1983 (FBN) - ESRI:115840

WKT

VERTCS["NAD_1983_(FBN)", 
	DATUM["NAD_1983_(Federal_Base_Network)", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["NAD_1983_(FBN)", 
	DATUM["NAD_1983_(Federal_Base_Network)", 
		ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
	CS[vertical, 1], 
	AXIS["Ellipsoidal height (h)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["Esri", "115840"]]

Data from @esri/proj-codes

{
  "wkid": 115840,
  "latestWkid": 115840,
  "macro": "PE_VCS_NAD_1983_FBN",
  "name": "NAD_1983_(FBN)",
  "wkt": "VERTCS[\"NAD_1983_(FBN)\",DATUM[\"NAD_1983_(Federal_Base_Network)\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"NAD_1983_(FBN)\",DATUM[\"NAD_1983_(Federal_Base_Network)\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],CS[vertical,1],AXIS[\"Ellipsoidal height (h)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"Esri\",\"115840\"]]",
  "description": "NAD 1983 (FBN)",
  "authority": "Esri",
  "version": "10.7.0",
  "deprecated": "no",
  "areaname": "USA - FBN",
  "extent": {
    "slat": -14.59,
    "nlat": 49.38,
    "llon": 144.58,
    "rlon": -64.51
  }
}