| NOS/NIMA | |
IHO/Foreign NIMA Charts |
|---|---|---|
| Chart Datum, Datum for sounding reduction | CD | |
| Lowest Astronomical Tide | LAT | |
| Highest Astronomical Tide | HAT | |
| MLW | Mean Low Water | MLW |
| MHW | Mean High Water | MHW |
| MLWS | Mean Low Water Springs | MLWS |
| MHWS | Mean High Water Springs | MHWS |
| MLWN | Mean Low Water Neaps | MLWN |
| MHWN | Mean High Water Neaps | MHWN |
| MLLW | Mean Lower Low Water | MLLW |
| MHHW | Mean Higher High Water | MHHW |
| Mean Higher Low Water | MHLW | |
| Mean Lower High Water | MLHW | |
| Sp | Spring tide | Sp |
| Np | Neap tide | Np |