Attribute: Vertical datum


Acronym: VERDAT

Code: 185

Attribute Type: E

Expected input:

ID Meaning INT 1 M-4
1 Mean low water springs
      
      
2 Mean lower low water springs
      
      
3 Mean sea level
      
      
4 Lowest low water
      
      
5 Mean low water
      
      
6 Lowest low water springs
      
      
7 Approximate mean low water springs
      
      
8 Indian spring low water
      
      
9 Low water springs
      
      
10 Approximate lowest astronomical tide
      
      
11 Nearly lowest low water
      
      
12 Mean lower low water
      
      
13 Low water
      
      
14 Approximate mean low water
      
      
15 Approximate mean lower low water
      
      
16 Mean high water
      
      
17 Mean high water springs
      
      
18 High water
      
      
19 Approximate mean sea level
      
      
20 High water springs
      
      
21 Mean higher high water
      
      
22 Equinoctial spring low water
      
      
23 Lowest astronomical tide
      
      
24 Local datum
      
      
25 International Great Lakes Datum 1985
      
      
26 Mean water level
      
      
27 Lower low water large tide
      
      
28 Higher high water large tide
      
      
29 Nearly highest high water
      
      
30 highest astronomical tide (HAT) NEW in S-57 Edition 3.1
      

Remarks: This attribute is used to specify the datum to which both heights (vertical datum, see S- 57 Part 3) and soundings (sounding datum, see S-57 Part 3) are referred.
When the vertical datum is unknown, such as water areas above locks, the value ‘local datum’ is to be used, and further details may be encoded using ‘INFORM’.
The 0.3m approximation quoted in the “approximate” levels is somehow arbitrary and follows the British example of their definition for “approximate LAT”.

Object Classes that use VERDAT