S-JTSK [JTSK03] - EPSG:8351

WKT

GEOGCS["S-
	JTSK_[JTSK03]", 
	DATUM["S-
		JTSK_[JTSK03]", 
		SPHEROID["Bessel_1841", 6377397.155, 299.1528128]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["S-
	JTSK_[JTSK03]", 
	DATUM["S-
		JTSK_[JTSK03]", 
		ELLIPSOID["Bessel_1841", 6377397.155, 299.1528128]], 
	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", "8351"]]

Data from @esri/proj-codes

{
  "wkid": 8351,
  "latestWkid": 8351,
  "macro": "PE_GCS_S_JTSK_JTSK03",
  "name": "S-JTSK_[JTSK03]",
  "wkt": "GEOGCS[\"S-JTSK_[JTSK03]\",DATUM[\"S-JTSK_[JTSK03]\",SPHEROID[\"Bessel_1841\",6377397.155,299.1528128]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"S-JTSK_[JTSK03]\",DATUM[\"S-JTSK_[JTSK03]\",ELLIPSOID[\"Bessel_1841\",6377397.155,299.1528128]],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\",\"8351\"]]",
  "description": "S-JTSK [JTSK03]",
  "authority": "EPSG",
  "version": "9.2.2(10.7.1)",
  "deprecated": "no",
  "areaname": "Slovakia",
  "extent": {
    "slat": 47.73,
    "nlat": 49.61,
    "llon": 16.84,
    "rlon": 22.56
  }
}