MONREF 1997 UTM Zone 50 N - ESRI:102228

WKT

PROJCS["MONREF_1997_UTM_Zone_50N", 
	GEOGCS["GCS_MONREF_1997", 
		DATUM["D_ITRF_2000", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Transverse_Mercator"], 
	PARAMETER["False_Easting", 500000.0], 
	PARAMETER["False_Northing", 0.0], 
	PARAMETER["Central_Meridian", 117.0], 
	PARAMETER["Scale_Factor", 0.9996], 
	PARAMETER["Latitude_Of_Origin", 0.0], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["MONREF_1997_UTM_Zone_50N", 
	BASEGEOGCRS["GCS_MONREF_1997", 
		DYNAMIC[
			FRAMEEPOCH[1997.0]], 
		DATUM["D_ITRF_2000", 
			ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Longitude (lon)", east, 
			ORDER[1]], 
		AXIS["Latitude (lat)", north, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Transverse_Mercator", 
		METHOD["Transverse_Mercator"], 
		PARAMETER["False_Easting", 500000.0], 
		PARAMETER["False_Northing", 0.0], 
		PARAMETER["Central_Meridian", 117.0], 
		PARAMETER["Scale_Factor", 0.9996], 
		PARAMETER["Latitude_Of_Origin", 0.0]], 
	CS[Cartesian, 2], 
	AXIS["Easting (X)", east, 
		ORDER[1]], 
	AXIS["Northing (Y)", north, 
		ORDER[2]], 
	LENGTHUNIT["Meter", 1.0], 
	ID["Esri", "102228"]]

Data from @esri/proj-codes

{
  "wkid": 102228,
  "latestWkid": 102228,
  "gcsWkid": 104134,
  "macro": "PE_PCS_MONREF_1997_UTM_50N",
  "name": "MONREF_1997_UTM_Zone_50N",
  "wkt": "PROJCS[\"MONREF_1997_UTM_Zone_50N\",GEOGCS[\"GCS_MONREF_1997\",DATUM[\"D_ITRF_2000\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",117.0],PARAMETER[\"Scale_Factor\",0.9996],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"MONREF_1997_UTM_Zone_50N\",BASEGEOGCRS[\"GCS_MONREF_1997\",DYNAMIC[FRAMEEPOCH[1997.0]],DATUM[\"D_ITRF_2000\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Transverse_Mercator\",METHOD[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",117.0],PARAMETER[\"Scale_Factor\",0.9996],PARAMETER[\"Latitude_Of_Origin\",0.0]],CS[Cartesian,2],AXIS[\"Easting (X)\",east,ORDER[1]],AXIS[\"Northing (Y)\",north,ORDER[2]],LENGTHUNIT[\"Meter\",1.0],ID[\"Esri\",\"102228\"]]",
  "description": "MONREF 1997 UTM Zone 50 N",
  "authority": "Esri",
  "version": "9.2.0",
  "deprecated": "no",
  "areaname": "Mongolia - east of 114~E",
  "extent": {
    "slat": 44.9,
    "nlat": 50.32,
    "llon": 114,
    "rlon": 119.94
  }
}