The accuracy of a coordinate can be measured in different ways, but by using the order classification we can describe accuracy in a consistent way. Order combines the absolute quality of the coordinate in relation to the datum (its tier) with the fit of the coordinate relative to nearby marks (its class), into a single category. In general, the lower the order number the more accurate a coordinate is.
There are 2 different order classifications. The first of these is for geometric coordinates (latitude, longitude, ellipsoidal height), used for New Zealand Geodetic Datum 2000 (NZGD2000) and Ross Sea Region Geodetic Datum 2000 (RSRGD2000). The second is for normal-orthometric heights, used for New Zealand Vertical Datum 2016 (NZVD16).
New Zealand Geodetic Datum 2000
Ross Sea Region Geodetic Datum 2000
New Zealand Vertical Datum 2016
Orders are defined in the Standard for tiers, classes, and orders of LINZ data (LINZS25006). They are summarised in the table below.
Standard for tiers, classes, and orders of LINZ data LINZS25006
Coordinate orders
| Order | Purpose | Tier (95% CI, m) | Class (95% CI) Constant (m) | Class (95% CI) Proportional (m/m) |
|---|---|---|---|---|
| 0 | National reference frame | H 0.05 V 0.05 | H 0.003 V 0.003 | H 0.000 000 03 V 0.000 000 03 |
| 1 | National deformation monitoring | H 0.05 V 0.10 | H 0.003 V 0.003 | H 0.000 000 1 V 0.000 000 3 |
| 2 | Regional deformation monitoring | H 0.10 V 0.25 | H 0.003 V 0.010 | H 0.000 001 V 0.000 003 |
| 3 | - | H 0.10 V 0.35 | H 0.01 V 0.01 | H 0.000 003 V 0.000 01 |
| 4 | Local deformation monitoring | H 0.15 V 0.35 | H 0.01 V 0.01 | H 0.000 01 V 0.000 03 |
| 5 | Cadastral horizontal control Basic geospatial network | H 0.15 V 0.35 | H 0.01 V 0.02 | H 0.000 05 V 0.000 1 |
| 6 | Cadastral permanent reference marks Cadastral witness marks | 0.15 | 0.03 | 0.000 15 |
| 7 | Class A boundary marks | 0.2 | 0.06 | 0.000 15 |
| 8 | Class B boundary marks | 0.5 | 0.3 | 0.000 6 |
| 9 | Class C boundary marks | 5 | 1 | 0.003 |
| 10 | - | 20 | 3 | 0.01 |
| 11 | - | 50 | 10 | 0.03 |
| 12 | - | - | - | - |
Notes:
- Orders 0 to 5 have different horizontal and vertical accuracy tolerances. For orders 6 to 11 the vertical tolerances are the same as the horizontal tolerances.
- Orders 0 to 8 are survey accurate and the class defines the local accuracy between marks. Order 6 is applied to Landonline survey accurate non-boundary marks, order 7 is applied to Class A boundary marks, and order 8 is applied to Class B boundary marks. (See Cadastral Survey Rules 2021)
- Orders 6 to 12 are not used for marks in the RSRGD2000 (Antarctica).
- Order 12 has no upper accuracy limit. It contains all coordinates with an accuracy less than order 11.
Height orders
| Order | Purpose | Tier (95% CI, m) | Class (95% CI) Constant (m) | Class (95% CI) Proportional (m/m) |
|---|---|---|---|---|
| 1V | National height network | 0.25 | 0.01 | 0.000 003 |
| 2V | - | 0.35 | 0.01 | 0.000 01 |
| 3V | Cadastral vertical control | 0.35 | 0.02 | 0.000 1 |
| 4V | - | 0.5 | 0.03 | 0.000 15 |
| 5V | - | 1 | 0.3 | 0.000 6 |
| 6V | - | - | - | - |
Notes:
- Order 6V has no accuracy upper accuracy limit. It contains all coordinates with an accuracy less than order 5V.