DKMSL depth (ensemble) - EPSG:10551

WKT

VERTCS["DKMSL_depth", 
	VDATUM["Denmark_Mean_Sea_Level"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", -1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["DKMSL_depth", 
	VDATUM["Denmark_Mean_Sea_Level"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", down, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "10551"]]

Data from @esri/proj-codes

{
  "wkid": 10551,
  "latestWkid": 10551,
  "macro": "PE_VCS_DKMSL_DEPTH",
  "name": "DKMSL_depth",
  "wkt": "VERTCS[\"DKMSL_depth\",VDATUM[\"Denmark_Mean_Sea_Level\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",-1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"DKMSL_depth\",VDATUM[\"Denmark_Mean_Sea_Level\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",down,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"10551\"]]",
  "description": "DKMSL depth (ensemble)",
  "authority": "EPSG",
  "version": "11.006(13.4.0)",
  "deprecated": "no",
  "areaname": "Denmark - offshore",
  "extent": {
    "slat": 54.36,
    "nlat": 58.27,
    "llon": 3.25,
    "rlon": 16.51
  }
}