SNN76 - EPSG:5785

WKT

VERTCS["SNN76", 
	VDATUM["SNN76"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["SNN76", 
	VDATUM["SNN76"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5785"]]

Data from @esri/proj-codes

{
  "wkid": 5785,
  "latestWkid": 5785,
  "macro": "PE_VCS_SNN76",
  "name": "SNN76",
  "wkt": "VERTCS[\"SNN76\",VDATUM[\"SNN76\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"SNN76\",VDATUM[\"SNN76\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5785\"]]",
  "description": "SNN76",
  "authority": "EPSG",
  "version": "6.7(9.3.0.0)",
  "deprecated": "no",
  "areaname": "Germany - East Germany all states",
  "extent": {
    "slat": 50.2,
    "nlat": 54.74,
    "llon": 9.92,
    "rlon": 15.04
  }
}