RGSPM06 (lon-lat) - ESRI:115911

WKT

VERTCS["RGSPM06_(lon-lat)", 
	DATUM["D_Reseau_Geodesique_de_St_Pierre_et_Miquelon_2006", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["RGSPM06_(lon-lat)", 
	DATUM["D_Reseau_Geodesique_de_St_Pierre_et_Miquelon_2006", 
		ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
	CS[vertical, 1], 
	AXIS["Ellipsoidal height (h)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["Esri", "115911"]]

Data from @esri/proj-codes

{
  "wkid": 115911,
  "latestWkid": 115911,
  "macro": "PE_VCS_RGSPM06_LON_LAT",
  "name": "RGSPM06_(lon-lat)",
  "wkt": "VERTCS[\"RGSPM06_(lon-lat)\",DATUM[\"D_Reseau_Geodesique_de_St_Pierre_et_Miquelon_2006\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"RGSPM06_(lon-lat)\",DATUM[\"D_Reseau_Geodesique_de_St_Pierre_et_Miquelon_2006\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],CS[vertical,1],AXIS[\"Ellipsoidal height (h)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"Esri\",\"115911\"]]",
  "description": "RGSPM06 (lon-lat)",
  "authority": "Esri",
  "version": "13.2.0",
  "deprecated": "no",
  "areaname": "St Pierre and Miquelon",
  "extent": {
    "slat": 43.41,
    "nlat": 47.37,
    "llon": -57.1,
    "rlon": -55.9
  }
}