Arc 1950 - EPSG:4209

WKT

GEOGCS["GCS_Arc_1950", 
	DATUM["D_Arc_1950", 
		SPHEROID["Clarke_1880_Arc", 6378249.145, 293.466307656]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_Arc_1950", 
	DATUM["D_Arc_1950", 
		ELLIPSOID["Clarke_1880_Arc", 6378249.145, 293.466307656]], 
	PRIMEM["Greenwich", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Latitude (lat)", north, 
		ORDER[1]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["EPSG", "4209"]]

Data from @esri/proj-codes

{
  "wkid": 4209,
  "latestWkid": 4209,
  "macro": "PE_GCS_ARC_1950",
  "name": "GCS_Arc_1950",
  "wkt": "GEOGCS[\"GCS_Arc_1950\",DATUM[\"D_Arc_1950\",SPHEROID[\"Clarke_1880_Arc\",6378249.145,293.466307656]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_Arc_1950\",DATUM[\"D_Arc_1950\",ELLIPSOID[\"Clarke_1880_Arc\",6378249.145,293.466307656]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"EPSG\",\"4209\"]]",
  "description": "Arc 1950",
  "authority": "EPSG",
  "version": "6.5(3.0.1)",
  "deprecated": "no",
  "areaname": "Africa - Botswana, Malawi, Zambia, Zimbabwe",
  "extent": {
    "slat": -26.88,
    "nlat": -8.19,
    "llon": 19.99,
    "rlon": 35.93
  }
}