# Coordinate system

## Detailed definition

A coordinate system is a reference system based on mathematical rules for specifying positions (locations) on the surface of the earth. The coordinate values can be spherical (latitude and longitude) using angular units of measure such as degrees, minutes and seconds or planar (Universal Transverse Mercator) using linear units such as metres.

Cartographic boundary files, digital boundary files, representative points and road network files are disseminated in latitude/longitude coordinates.

## Censuses

2011, 2006, 2001, 1996, 1991, 1986, 1981 (latitude/longitude)

1996, 1991, 1986, 1981, 1976, 1971 (Universal Transverse Mercator)

## Remarks

A coordinate system is usually defined by a datum, ellipsoid and projection, and is specified in terms of units (e.g., degrees, metres).

Latitude and longitude coordinates, often referred to as geographic coordinates, are spherical. Lines of latitude (also called parallels) run in an east-west direction around the earth parallel to the equator. Latitude is the angular measurement of a location expressed in degrees north or south of the equator, ranging from 0° at the equator to 90°N or 90°S at the poles. Lines of longitude (also called meridians) run in a north-south direction from pole to pole. Longitude is the angular measurement of a location east or west of the prime meridian (which runs through Greenwich, England), ranging from 0° at the prime meridian to 180°E or 180°W. The 180^{th} meridian is the approximate location of the International Date Line.

For the land mass of Canada, latitudes range from about 42^{o}N to 83^{o}N and longitudes range from approximately 53°W to 141°W.

Latitude coordinates south of the equator and longitude coordinates west of the prime meridian have minus signs when stored in a digital database. Latitude/longitude coordinates are convenient for transferring and disseminating spatial digital data, and are normally expressed in decimal degrees on a database. However, maps should not be generated using these spherical coordinates, as they are **unprojected**, resulting in a map that appears distorted (see Figure 14 in map projection definition).

It is now common for geographic information system (GIS) software to convert coordinates from one frame of reference to coordinates of another frame of reference, such as transforming the Lambert conformal conic projection to latitude/longitude coordinates.

The Universal Transverse Mercator (UTM) coordinate system is no longer used as the working coordinate system or for disseminating spatial digital data.

Refer to related definitions of cartographic boundary files (CBFs); datum; digital boundary files (DBFs); map projection; representative point; road network file (RNF) and Spatial Data Infrastructure (SDI).

## Changes prior to the current census

For 1996, street network files were disseminated in latitude/longitude coordinates, but the working coordinate system was UTM.

Prior to 1996, street network files were disseminated in UTM coordinates only.