ISN 2004 - ESRI:104144

WKT

GEOGCS["GCS_ISN_2004", 
	DATUM["D_Islands_Network_2004", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_ISN_2004", 
	DATUM["D_Islands_Network_2004", 
		ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Latitude (lat)", north, 
		ORDER[1]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["Esri", "5324"]]

Data from @esri/proj-codes

{
  "wkid": 104144,
  "latestWkid": 5324,
  "macro": "PE_GCS_ISN_2004",
  "name": "GCS_ISN_2004",
  "wkt": "GEOGCS[\"GCS_ISN_2004\",DATUM[\"D_Islands_Network_2004\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_ISN_2004\",DATUM[\"D_Islands_Network_2004\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"Esri\",\"5324\"]]",
  "description": "ISN 2004",
  "authority": "Esri",
  "version": "10.0.0",
  "deprecated": "codechange",
  "areaname": "Iceland",
  "extent": {
    "slat": 59.96,
    "nlat": 69.59,
    "llon": -30.87,
    "rlon": -5.55
  }
}