EUREF-FIN GK31FIN - EPSG:3885

WKT

PROJCS["EUREF-FIN_GK31FIN", 
	GEOGCS["GCS_EUREF_FIN", 
		DATUM["EUREF-FIN", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Gauss_Kruger"], 
	PARAMETER["False_Easting", 31500000.0], 
	PARAMETER["False_Northing", 0.0], 
	PARAMETER["Central_Meridian", 31.0], 
	PARAMETER["Scale_Factor", 1.0], 
	PARAMETER["Latitude_Of_Origin", 0.0], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["EUREF-FIN_GK31FIN", 
	BASEGEOGCRS["GCS_EUREF_FIN", 
		DATUM["EUREF-FIN", 
			ELLIPSOID["GRS_1980", 6378137.0, 298.257222101], 
			ANCHOREPOCH[1997.0]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Latitude (lat)", north, 
			ORDER[1]], 
		AXIS["Longitude (lon)", east, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Gauss_Kruger", 
		METHOD["Gauss_Kruger"], 
		PARAMETER["False_Easting", 31500000.0], 
		PARAMETER["False_Northing", 0.0], 
		PARAMETER["Central_Meridian", 31.0], 
		PARAMETER["Scale_Factor", 1.0], 
		PARAMETER["Latitude_Of_Origin", 0.0]], 
	CS[Cartesian, 2], 
	AXIS["Northing (Y)", north, 
		ORDER[1]], 
	AXIS["Easting (X)", east, 
		ORDER[2]], 
	LENGTHUNIT["Meter", 1.0], 
	ID["EPSG", "3885"]]

Data from @esri/proj-codes

{
  "wkid": 3885,
  "latestWkid": 3885,
  "gcsWkid": 10690,
  "macro": "PE_PCS_ETRS_1989_GK31FIN",
  "name": "EUREF-FIN_GK31FIN",
  "wkt": "PROJCS[\"EUREF-FIN_GK31FIN\",GEOGCS[\"GCS_EUREF_FIN\",DATUM[\"EUREF-FIN\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Gauss_Kruger\"],PARAMETER[\"False_Easting\",31500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",31.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"EUREF-FIN_GK31FIN\",BASEGEOGCRS[\"GCS_EUREF_FIN\",DATUM[\"EUREF-FIN\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101],ANCHOREPOCH[1997.0]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Gauss_Kruger\",METHOD[\"Gauss_Kruger\"],PARAMETER[\"False_Easting\",31500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",31.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0]],CS[Cartesian,2],AXIS[\"Northing (Y)\",north,ORDER[1]],AXIS[\"Easting (X)\",east,ORDER[2]],LENGTHUNIT[\"Meter\",1.0],ID[\"EPSG\",\"3885\"]]",
  "description": "EUREF-FIN GK31FIN",
  "authority": "EPSG",
  "version": "7.5.1(10.1.0)",
  "deprecated": "no",
  "areaname": "Finland - east of 30.5~E nominal",
  "extent": {
    "slat": 62.08,
    "nlat": 64.27,
    "llon": 30.5,
    "rlon": 31.59
  }
}