ISO 6709 - AbsoluteAstronomy.com

ISO 6709 Standard representation of geographic point location by coordinates is the international standard

International standard

International standards are standards developed by international standards organizations. International standards are available for consideration and use, worldwide...

for representation of latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

, longitude

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

and altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

for geographic point locations.

The first edition (ISO 6709:1983) was developed by ISO/IEC JTC 1/SC 32. Later the standard was transferred to ISO/TC211, Geographic information/Geomatics in 2001. The committee completely revised the second edition (ISO 6709:2008).

The second edition consists of a main part and eight annexes (Annexes A through H). The main part and Annexes A and C give encoding-independent general rules to define items to specify geographic point(s). Annex D suggests a display style for human interface. Annexes F and G suggest styles of XML

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

expression. Annex H suggests string expression, which supersedes the first edition of the standard.

Items

A geographical point is specified by the following four items:

First horizontal coordinate (x), such as latitude
Second horizontal coordinate (y), such as longitude
Vertical coordinate, i.e. height or depth (optional)
Identification of coordinate reference system (CRS) (optional)

The first three items are numerical values called coordinates. The CRS gives the relationship between the coordinates and a point on the earth. The identification of CRS could be a full description of properties defined in ISO 19111; only an identifier given by some registry (such as EPSG) is used in most cases, since only such identification is enough for most information exchange purposes.

Order, sign, and units

Order, positive direction, and units of coordinates are supposed to be defined by the CRS. When CRS identification is missing, the data must be interpreted by the following conventions:

Longitude comes after latitude
North latitude is positive
East longitude is positive
Fraction of degrees is preferred in digital data exchange, while sexagesimal notation is tolerated for compatibility

There is no such interpretation rule for vertical coordinates.

String expression (Annex H)

A string expression of a point consists of latitude, longitude, height or depth, CRS identifier, and trailing solidus (/) without any delimiting character. When height or depth is used, there must be CRS identifier.

Latitude

Latitude is a number preceded by a sign character. A plus sign (+) denotes northern hemisphere or the equator, and a minus sign (-) denotes southern hemisphere.

The integer part of the number is a fixed length. The number of digits in that part indicates the units, thus leading zero(es) must be filled when necessary. The fractional part must have the appropriate number of digits to represent the required precision of the coordinate.

num. digits	units	format	example
2	deg	±DD	+40.20361
4	deg, min	±DDMM	+4012.22
6	deg, min, sec	±DDMMSS	+401213.1

Longitude

Longitude is a number preceded by a sign character. A plus sign (+) denotes east longitude or the prime meridian

Prime Meridian

The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...

, and a minus sign (-) denotes west longitude or 180° meridian (opposite of the prime meridian).

Rules about the number of digits are same to latitude.

num. digits	units	format	example
3	deg	±DDD	-075.00417
5	deg, min	±DDDMM	-07500.25
7	deg, min, sec	±DDDMMSS	-0750015.1

Height or depth

When height or depth is present, CRS identifier must follow.
Positive direction and units are defined by CRS.
Negative number does not necessarily mean position below reference level.
Positive is up for height, down for depth.

CRS identifier

The CRS identifier begins with "CRS". There are three styles:

When a registry provides online resolver, CRS<url>
When a registry is offline, CRSregistry:crsid
When the data creator provides full definition of CRS using ISO 19111, CRS<CRSID>

The example of original Annex H always use "CRSWGS_84".

Examples

Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

+00-025/
France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

+46+002/
- Paris
  Paris
  Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
  
  +48.52+002.20/
  - Eiffel Tower
    Eiffel Tower
    The Eiffel Tower is a puddle iron lattice tower located on the Champ de Mars in Paris. Built in 1889, it has become both a global icon of France and one of the most recognizable structures in the world...
    
    +48.8577+002.295/
Mount Everest
Mount Everest
Mount Everest is the world's highest mountain, with a peak at above sea level. It is located in the Mahalangur section of the Himalayas. The international boundary runs across the precise summit point...

+27.5916+086.5640+8850CRSWGS_84/
North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...

+90+000/
Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

+00-160/
South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...

-90+000+2800CRSWGS_84/
United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

+38-097/
- New York City
  New York City
  New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
  
  +40.75-074.00/
  - Statue of Liberty
    Statue of Liberty
    The Statue of Liberty is a colossal neoclassical sculpture on Liberty Island in New York Harbor, designed by Frédéric Bartholdi and dedicated on October 28, 1886...
    
    +40.6894-074.0447/

XML Representation (Annex F)

The XML representation based on the conceptual model of Annex C uses XML namespace http://www.isotc211.org/2006/gpl. However there is no published XML Schema at the time of writing (August 2011).





  

    35.89421911 139.94637467

Representation for Human Interface (Annex D)

When there is no guideline given from the user community, the following styles are suggested:

Coordinate values (latitude, longitude, and altitude) should be delimited by spaces.
The decimal point is a part of the value, thus must usually be configured by the operating system.
Multiple points should be represented by multiple lines.
Latitude and longitude should be displayed by sexagesimal fractions (i.e. minutes and seconds).
When minutes and seconds are less than ten, leading zeroes should be shown.
Degree, minutes and seconds should be followed by the symbols ° (U+00B0), ' (U+0027), and " (U+0022), without spaces between the number and symbol.
North and south latitudes should be indicated by N and S following immediately after the digits.
East and west longitudes should be indicated by E and W following immediately after the digits.
Units of elevation or depth should be given by symbols, immediately after the digits.
Elevation below reference level or depth above reference level should be indicated by a minus sign (-).

Examples:

50°40'46,461"N 95° 48'26,533"W 1 123,45m
50°03'46,461"S 125° 48'26,533"E 978,90m

Standards

Implementations

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