Data Standards
The following are data standards used in the Ontario Natural Heritage Information Centre (NHIC) databases.
Where possible, they are based on existing Ontario Ministry of Natural Resources (OMNR) standards, or standards
used in the Biological and Conservation Data (BCD) System developed by The Nature Conservancy based in
Arlington, VA. Individuals and organizations which contribute data to the NHIC are encouraged to use any of
these standards which apply when designing their own databases.
Values in parentheses are alternate names for the fields. The type of field is listed as either character (C)
or numeric (N), followed by the number of characters or digits. For numeric fields the number of decimal
places is shown following the decimal point.
General:
Metric measurements are used throughout the databases. Distances are in meters or km, elevations are in
meters, and areas are measured in hectares. Dates are stored as date fields if possible, or as text if
dates are sometimes incomplete (e.g. only the year is known). If stored as text, a "YYYY-MM-DD" format is
used. UTM Coordinates are based on the 6 degree UTM reference system, adopted as a Provincial standard
in 1974.
UTM_ZONE (ZONE) N(2.0)
Zone number (6 degrees longitude in width):
15 Between Long. 96 and 90 W
16 Between Long. 90 and 84 W
17 Between Long. 84 and 78 W
18 Between Long. 78 and 72 W
UTM_EASTING (EASTING) N(6.0)
Easting within a zone (meters). Allowable values are between 200,000 and 800,000.
UTM_NORTHING (NORTHING) N(7.0)
Meters north of the equator. Allowable values in Ontario are between 4,000,000 and 7,000,000.
UTM (FULL_UTM) C(17)
Single 17-character field containing ZONE, EASTING, NORTHING values separated by commas. This is used
as an alternative to using the three fields separately, and is useful as a key field if repetitive
locational information is kept separate from other observation data.
UTM_GRID (GRID) C(6)
The 2nd, 3rd, and 4th digit of the EASTING combined with the 3rd, 4th and 5th digit of the NORTHING.
Must be accompanied by a MAPNUM to be useful. ZONE, EASTING, and NORTHING values can be calculated
from this if a valid MAPSQUARE has also been entered.
UTM_ACCURACY (ACC) C(1)
The level of accuracy of the Easting and Northing data:
0 accurate to within 1 m accuracy
1 within 10 m
2 within 100 m
3 within 1,000 m
4 within 10,000 m (mappable to 10 km square only)
5 greater than 10,000 m accuracy (unmappable)
UTM_DATUM (DATUM) C(10)
Geodetic datum which UTM is based on (e.g. NAD27, NAD83, WGS84). The UTM coordinates of a point are
usually determined from a grid printed on the Federal NTS and on the OBM series of maps. The position
and numbering of the grid on the map sheet is determined on the basis of the position of the map relative
to a geodetic datum. Many maps are based upon a datum known as the North American 1927 Datum (NAD27).
There has been a revision to the datum (known as the 1983 datum (NAD83)), leading to a revised grid on
newer maps. This could result in discrepancies of up to 200m between the two versions. For example,
if someone was trying to find a mine shaft using coordinates based on the 1927 datum but was using a
map based on the 1983 datum, the coordinates could suggest that the shaft was on the wrong side of a
lake. The datum on which a map is based is shown on the bottom of the map. Eventually, all maps will
be based upon the NAD83 and all coordinates will be consistent. In the interim, however, it is important
to record the DATUM on which the coordinates were developed.
NTS_MAPNUM (MAPNUM) C(13)
Canadian National Topographic Series map number. Consists of 2 numerals, 1 letter, and a slash (/),
followed by various numerals (e.g. 40P/9). In BCD this field is called QUADCODE.
MAPSQUARE (SQUARE) C(6)
A 10 km x 10 km square used as the main unit in many atlas projects, such as the Atlas of the Breeding
Birds of Ontario. Consists of 2-digit UTM ZONE, followed by 2-letter 100 km block code, followed by
2-digit 10 km value (e.g. 17PU96).
OBM_MAPNUM (OBM) C(20)
Ontario Base Map number in the following format: SS ZZ EEEE NNNNN where SS denotes the map scale
(10=1:10000, 20=1:20000), ZZ is the UTM ZONE number, EEEE and NNNNN are the EASTING and NORTHING
values (rounded and truncated) of the southwest corner of the map. Note the spaces between the
four parts of the map number.
COUNTYCODE C(4)
A 4-character code denoting county, district, or regional municipality (upper-tier). Consists of
the first 4 letters of the county, etc. (e.g. STOR = Stormont, Dundas and Glengarry). BCD appends
a 2-character State/Province code to the beginning of the code (e.g. ONSTOR), to uniquely identify
counties across jurisdictions.
MUNICIP_CODE C(5)
A 5-digit code denoting the lower tier municipality (municipal township). The codes are looked up
from an OMNR corporate table called MUNICIPALITIES which contains codes and standardized names
for several levels of municipalities. The codes are those used by the Ontario Ministry of Municipal
Affairs, are adopted as a OMNR standard and are in common use in the Federal Government.
GEO_TWP_CODE (TOWNSHIP) C(6)
A 6-digit code denoting the geographic township. The codes are looked up from a corporate OMNR
table called GEOGRAPHIC_TOWNSHIPS.
Much (but not all) of Ontario is divided into non-overlapping, legally-defined (by original surveys)
geographic townships. Being purely geographic in nature, these areas should not to be confused with
municipal townships, which have been defined for administrative purposes.
