Datum,Datum Field Description,Reference
0,Reserved,[RFC6225]
1,Vertical datum WGS 84 defined by EPSG CRS Code 4327,[RFC6225]
2,Vertical datum NAD83 defined by EPSG CRS Code 4269 with North American Vertical Datum of 1988 (NAVD88),[RFC6225]
3,Vertical datum NAD83 defined by EPSG CRS Code 4269 with Mean Lower Low Water (MLLW) as associated vertical datum,[RFC6225]
4-7,Unassigned,