NGG 1977 - EPSG:5755

WKT

VERTCS["NGG_1977", 
	VDATUM["Nivellement_General_Guyanais_1977"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["NGG_1977", 
	VDATUM["Nivellement_General_Guyanais_1977"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5755"]]

Data from @esri/proj-codes

{
  "wkid": 5755,
  "latestWkid": 5755,
  "macro": "PE_VCS_NGG_1977",
  "name": "NGG_1977",
  "wkt": "VERTCS[\"NGG_1977\",VDATUM[\"Nivellement_General_Guyanais_1977\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"NGG_1977\",VDATUM[\"Nivellement_General_Guyanais_1977\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5755\"]]",
  "description": "NGG 1977",
  "authority": "EPSG",
  "version": "6.15(9.3.0.0)",
  "deprecated": "no",
  "areaname": "French Guiana - onshore",
  "extent": {
    "slat": 2.11,
    "nlat": 5.81,
    "llon": -54.61,
    "rlon": -51.61
  }
}