Hydrography and nautical charting.
Approximate because not specific to any location or epoch. Users are advised to not use this generic CRS but instead use one with a specific datum origin (e.g. "HHWLT at xxx during yyyy-yyyy") or defined through a specified geoid/hydroid model.
Definition: OGC Well Known Text 2 (2019)
VERTCRS["HHWLT height", VDATUM["Higher High Water Large Tide"], CS[vertical,1], AXIS["gravity-related height (H)",up, LENGTHUNIT["metre",1]], USAGE[ SCOPE["Hydrography and nautical charting."], AREA["World."], BBOX[-90,-180,90,180]], ID["EPSG",5871]]
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "VerticalCRS", "name": "HHWLT height", "datum": { "type": "VerticalReferenceFrame", "name": "Higher High Water Large Tide" }, "coordinate_system": { "subtype": "vertical", "axis": [ { "name": "Gravity-related height", "abbreviation": "H", "direction": "up", "unit": "metre" } ] }, "scope": "Hydrography and nautical charting.", "area": "World.", "bbox": { "south_latitude": -90, "west_longitude": -180, "north_latitude": 90, "east_longitude": 180 }, "id": { "authority": "EPSG", "code": 5871 } }
Definition: Mapnik
<?xml version="1.0" encoding="utf-8"?> <Map srs="+vunits=m +no_defs +type=crs"> <Layer srs="+vunits=m +no_defs +type=crs"> </Layer> </Map>
Definition: SQL (PostGIS)
INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 5871, 'EPSG', 5871, '+vunits=m +no_defs +type=crs', 'VERT_CS["HHWLT height",VERT_DATUM["Higher High Water Large Tide",2005,AUTHORITY["EPSG","1084"]],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","5871"]]');