IGCB 1955 - EPSG:4701

WKT

GEOGCS["GCS_IGCB_1955", 
	DATUM["D_Institut_Geographique_du_Congo_Belge_1955", 
		SPHEROID["Clarke_1880_RGS", 6378249.145, 293.465]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_IGCB_1955", 
	DATUM["D_Institut_Geographique_du_Congo_Belge_1955", 
		ELLIPSOID["Clarke_1880_RGS", 6378249.145, 293.465]], 
	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", "4701"]]

Data from @esri/proj-codes

{
  "wkid": 4701,
  "latestWkid": 4701,
  "macro": "PE_GCS_IGCB_1955",
  "name": "GCS_IGCB_1955",
  "wkt": "GEOGCS[\"GCS_IGCB_1955\",DATUM[\"D_Institut_Geographique_du_Congo_Belge_1955\",SPHEROID[\"Clarke_1880_RGS\",6378249.145,293.465]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_IGCB_1955\",DATUM[\"D_Institut_Geographique_du_Congo_Belge_1955\",ELLIPSOID[\"Clarke_1880_RGS\",6378249.145,293.465]],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\",\"4701\"]]",
  "description": "IGCB 1955",
  "authority": "EPSG",
  "version": "6.9(9.2.0)",
  "deprecated": "no",
  "areaname": "Congo DR (Zaire) - Bas Congo",
  "extent": {
    "slat": -6.04,
    "nlat": -4.28,
    "llon": 12.17,
    "rlon": 16.28
  }
}