NZ Topo - object class canal_poly

This page describe the canal_poly object class used to represent objects in the NZTopo topographic database.


An artificial open waterway used for transportation, waterpower or irrigation.

Topo50 description

Canal_poly is used to capture canals where they are large enough to hold at 1:50,000 as an area feature. Narrower canals are captured as a centreline. Where a canal is close to a road, the position held in the data is as close to it's true position as capture techniques permit. This may result in part of the canal feature being obscurred by the road symbol. Other objects completing the water-flow pattern are: river, lake, swamp, water race,pond, lagoon and pipeline_cl (where pipeline_use = 'water)

Representation specification

Representation specification showing canal_poly

Click to enlarge image

See also: siphon_poly canal_cl

Class attributes

Object classcanal_poly
Additional entity classNot applicable
Object inheritancesimple_area
Entity sourceUS Standard Entity
Map series Topo50 Topo250
LSLIFF object class303

Object attributes

AttributeLSLIFF code
Shapefile field
Data type
Attribute descriptionAttribute values*
Name of the canal, where known. Text data from July 2012 will be in UTF-8 format. If your system is not UTF-8 compliant, you will need to use the name_ascii attribute, which has had any macronated vowels removed. UTF-8 stands for Unicode Transformation Format-8. It is an octet (8-bit) lossless encoding of Unicode characters. UTF-8 encodes each Unicode character as a variable number of 1 to 4 octets, where the number of octets depends on the integer value assigned to the Unicode character. It is an efficient encoding of Unicode documents that use mostly US-ASCII characters because it represents each character in the range U+0000 through U+007F as a single octet. UTF-8 is the default encoding for XML.
"Oakden Canal"
Indicates whether the entry in the name_ascii field contains a macronated vowel. Where the value is "Y" go to for a list of places or feature names within New Zealand that are gazetted and include macrons
Text data from July 2012 will be in UTF-8 format. If your system is not UTF-8 compliant, you will need to use this attribute, which has had any macronated vowels removed.
A unique identifier for use on Topo50 data in the LINZ Data Service. This is not a universal ID. The intention is to manage these ID’s as persistent, however this is not guaranteed and there will be instances where what appears to be a minor change to a feature may result in a new ID being assigned.

* See explanation of attribute values for more information about how attribute values are represented.

Change log

Feature versionRevisedDescription
92014-11-14Updated definition
82012-08-28Updated map image and aerial view; added representation specification and example feature photographs
72012-08-28Added scale-specific definitions
62012-08-28Added scale-specific definitions
52012-08-16Name attribute in UTF-8 format; added name_ascii attribute
42010-03-01Added name_macronated attribute
32008-04-10Removed reference to seed and void objects
22001-11-23Unspecified update
11999-03-01intial status