ISTS 073 Astro 1969 - EPSG:4724

WKT

GEOGCS["GCS_ISTS_073_1969", 
	DATUM["D_ISTS_073_1969", 
		SPHEROID["International_1924", 6378388.0, 297.0]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_ISTS_073_1969", 
	DATUM["D_ISTS_073_1969", 
		ELLIPSOID["International_1924", 6378388.0, 297.0]], 
	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", "4724"]]

Data from @esri/proj-codes

{
  "wkid": 4724,
  "latestWkid": 4724,
  "macro": "PE_GCS_ISTS_073_1969",
  "name": "GCS_ISTS_073_1969",
  "wkt": "GEOGCS[\"GCS_ISTS_073_1969\",DATUM[\"D_ISTS_073_1969\",SPHEROID[\"International_1924\",6378388.0,297.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_ISTS_073_1969\",DATUM[\"D_ISTS_073_1969\",ELLIPSOID[\"International_1924\",6378388.0,297.0]],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\",\"4724\"]]",
  "description": "ISTS 073 Astro 1969",
  "authority": "EPSG",
  "version": "6.9(9.3.0.0)",
  "deprecated": "no",
  "areaname": "British Indian Ocean Territory - Diego Garcia",
  "extent": {
    "slat": -7.49,
    "nlat": -7.18,
    "llon": 72.3,
    "rlon": 72.55
  }
}