This document has been superseded. Everyone should refer instead to the Content Standard for Digital Geospatial Metadata, officially known as FGDC-STD-001-1998, dated June 1998, at the web site of the Federal Geographic Data Committee.

Content standards for digital geospatial metadata -- FGDC

4: Spatial Reference Information -- the description of the reference frame for, and the means to encode, coordinates in the data set.

Syntax:

Spatial_Reference_Information =
0{Horizontal_Coordinate_System_Definition}1 + 0{Vertical_Coordinate_System_Definition}1
Horizontal_Coordinate_System_Definition =
[Geographic | 1{Planar}n | Local] + 0{Geodetic_Model}1
Geographic =
Latitude_Resolution + Longitude_Resolution + Geographic_Coordinate_Units
Planar =
[Map_Projection | Grid_Coordinate_System | Local_Planar] + Planar_Coordinate_Information
Map_Projection =
Map_Projection_Name + [Albers_Conical_Equal_Area | Azimuthal_Equidistant | Equidistant_Conic | Equirectangular | General_Vertical_Near-sided_Perspective | Gnomonic | Lambert_Azimuthal_Equal_Area | Lambert_Conformal_Conic | Mercator | Modified_Stereographic_for_Alaska | Miller_Cylindrical | Oblique_Mercator | Orthographic | Polar_Stereographic | Polyconic | Robinson | Sinusoidal | Space_Oblique_Mercator_(Landsat) | Stereographic | Transverse Mercator | van_der_Grinten | Other_Projection's_Definition]
Albers_Conical_Equal_Area =
1{Standard_Parallel}2 + Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
Azimuthal_Equidistant =
Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
Equidistant_Conic =
1{Standard_Parallel}2 + Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
Equirectangular =
Standard_Parallel + Longitude_of_Central_Meridian + False_Easting + False_Northing
General_Vertical_Near-sided_Projection =
Height_of_Perspective_Point_Above_Surface + Longitude_of_Projection_Center + Latitude_of_Projection_Center + False_Easting + False_Northing
Gnomonic =
Longitude_of_Projection_Center + Latitude_of_Projection_Center + False_Easting + False_Northing
Lambert_Azimuthal_Equal_Area =
Longitude_of_Projection_Center + Latitude_of_Projection_Center + False_Easting + False_Northing
Lambert_Conformal_Conic =
1{Standard_Parallel}2 + Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
Mercator =
[Standard_Parallel | Scale_Factor_at_Equator] + Longitude_of_Central_Meridian + False_Easting + False_Northing
Modified_Stereographic_for_Alaska =
False_Easting + False_Northing
Miller_Cylindrical =
Longitude_of_Central_Meridian + False_Easting + False_Northing
Oblique_Mercator =
Scale_Factor_at_Center_Line + [Oblique_Line_Azimuth | Oblique_Line_Point] + Latitude_of_Projection_Origin + False_Easting + False_Northing
Oblique_Line_Azimuth =
Azimuthal_Angle + Azimuth_Measure_Point_Longitude
Oblique_Line_Point =
2{Oblique_Line_Latitude + Oblique_Line_Longitude}2
Orthographic =
Longitude_of_Projection_Center + Latitude_of_Projection_Center + False_Easting + False_Northing
Polar_Stereographic =
Straight_Vertical_Longitude_from_Pole + [Standard_Parallel | Scale_Factor_at_Projection_Origin] + False_Easting + False_Northing
Polyconic =
Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
Robinson =
Longitude_of_Projection_Center + False_Easting + False_Northing
Sinusoidal =
Longitude_of_Central_Meridian + False_Easting + False_Northing
Space_Oblique_Mercator_(Landsat) =
Landsat_Number + Path_Number + False_Easting + False_Northing
Stereographic =
Longitude_of_Projection_Center + Latitude_of_Projection_Center + False_Easting + False_Northing
Transverse_Mercator =
Scale_Factor_at_Central_Meridian + Longitude_of_Central_Meridian + Latitude_of_Projection_Origin + False_Easting + False_Northing
van_der_Grinten =
Longitude_of_Central_Meridian + False_Easting + False_Northing
Grid_Coordinate_System =
Grid_Coordinate_System_Name + [Universal_Transverse_Mercator | Universal_Polar_Stereographic | State_Plane_Coordinate_System | ARC_Coordinate_System | Other_Grid_System's_Definition]
Universal_Transverse_Mercator =
UTM_Zone_Number + Transverse_Mercator
Universal_Polar_Stereographic =
UPS_Zone_Identifier + Polar_Stereographic
State_Plane_Coordinate_System =
SPCS_Zone_Identifier + [Lambert_Conformal_Conic | Transverse_Mercator | Oblique_Mercator | Polyconic]
ARC_Coordinate_System =
ARC_System_Zone_Identifier + [Equirectangular | Azimuthal_Equidistant]
Local_Planar =
Local_Planar_Description + Local_Planar_Georeference_Information
Planar_Coordinate_Information =
Planar_Coordinate_Encoding_Method + [Coordinate_Representation | Distance_and_Bearing_Representation] + Planar_Distance_Units
Coordinate_Representation =
Abscissa_Resolution + Ordinate_Resolution
Distance_and_Bearing_Representation =
Distance_Resolution + Bearing_Resolution + Bearing_Units + Bearing_Reference_Direction + Bearing_Reference_Meridian
Local =
Local_Description + Local_Georeference_Information
Geodetic_Model =
0{Horizontal_Datum_Name}1 + Ellipsoid_Name + Semi-major_Axis + Denominator_of_Flattening_Ratio
Vertical_Coordinate_System_Definition =
0{Altitude_System_Definition}1 + 0{Depth_System_Definition}1
Altitude_System_Definition =
Altitude_Datum_Name + 1{Altitude_Resolution}n + Altitude_Distance_Units + Altitude_Encoding_Method
Depth_System_Definition =
Depth_Datum_Name + 1{Depth_Resolution}n + Depth_Distance_Units + Depth_Encoding_Method

Semantics:

Horizontal Coordinate System Definition -- 4.1
the reference frame or system from which linear or angular quantities are measured and assigned to the position that a point occupies. Compound.
Geographic -- 4.1.1
the quantities of latitude and longitude which define the position of a point on the Earth's surface with respect to a reference spheroid. Compound.
Latitude Resolution -- 4.1.1.1
the minimum difference between two adjacent latitude values expressed in Geographic Coordinate Units of measure.
Type: real
Domain: Latitude Resolution > 0.0
Longitude Resolution -- 4.1.1.2
the minimum difference between two adjacent longitude values expressed in Geographic Coordinate Units of measure.
Type: real
Domain: Longitude Resolution > 0.0
Geographic Coordinate Units -- 4.1.1.3
units of measure used for the latitude and longitude values.
Type: text
Domain: "Decimal degrees" "Decimal minutes" "Decimal seconds" "Degrees and decimal minutes" "Degrees, minutes, and decimal seconds" "Radians" "Grads"
Planar -- 4.1.2
the quantities of distances, or distances and angles, which define the position of a point on a reference plane to which the surface of the Earth has been projected. Compound.
Map Projection -- 4.1.2.1
the systematic representation of all or part of the surface of the Earth on a plane or developable surface. Compound.
Map Projection Name -- 4.1.2.1.1
name of the map projection.
Type: text
Domain:
"Albers Conical Equal Area"
"Azimuthal Equidistant"
"Equidistant Conic"
"Equirectangular"
"General Vertical Near-sided Projection"
"Gnomonic"
"Lambert Azimuthal Equal Area"
"Lambert Conformal Conic"
"Mercator"
"Modified Stereographic for Alaska"
"Miller Cylindrical"
"Oblique Mercator"
"Orthographic"
"Polar Stereographic"
"Polyconic"
"Robinson"
"Sinusoidal"
"Space Oblique Mercator"
"Stereographic"
"Transverse Mercator"
"van der Grinten"
"other projection"
(Map projection parameters for specific projections) -- 4.1.2.1.2
parameters for a specific map projection, each having a unique mathematical relationship between the Earth and the plane or developable surface. Compound.
(The data elements 4.1.2.1.2.1 through 4.1.2.1.2.17 are map projection parameters. Each map projection has a specific set of defining parameters. These sets of parameters are provided in the syntax for each projection.)
Standard Parallel -- 4.1.2.1.2.1
line of constant latitude at which the surface of the Earth and the plane or developable surface intersect.
Type: real
Domain: -90.0 <= Standard Parallel <= 90.0
Longitude of Central Meridian -- 4.1.2.1.2.2
the line of longitude at the center of a map projection generally used as the basis for constructing the projection.
Type: real
Domain: -180.0 <= Longitude of Central Meridian < 180.0
Latitude of Projection Origin -- 4.1.2.1.2.3
latitude chosen as the origin of rectangular coordinates for a map projection.
Type: real
Domain: -90.0 <= Latitude of Projection Origin <= 90.0
False Easting -- 4.1.2.1.2.4
the value added to all "x" values in the rectangular coordinates for a map projection. This value frequently is assigned to eliminate negative numbers. Expressed in the unit of measure identified in Planar Coordinate Units.
Type: real
Domain: free real
False Northing -- 4.1.2.1.2.5
the value added to all "y" values in the rectangular coordinates for a map projection. This value frequently is assigned to eliminate negative numbers. Expressed in the unit of measure identified in Planar Coordinate Units.
Type: real
Domain: free real
Scale Factor at Equator -- 4.1.2.1.2.6
a multiplier for reducing a distance obtained from a map by computation or scaling to the actual distance along the equator.
Type: real
Domain: Scale Factor at Equator > 0.0
Height of Perspective Point Above Surface -- 4.1.2.1.2.7
height of viewpoint above the Earth, expressed in meters.
Type: real
Domain: Height of Perspective Point Above Surface > 0.0
Longitude of Projection Center -- 4.1.2.1.2.8
longitude of the point of projection for azimuthal projections.
Type: real
Domain: -180.0 <= Longitude of Projection Center < 180.0
Latitude of Projection Center -- 4.1.2.1.2.9
latitude of the point of projection for azimuthal projections.
Type: real
Domain: -90.0 <= Latitude of Projection Center <= 90.0
Scale Factor at Center Line -- 4.1.2.1.2.10
a multiplier for reducing a distance obtained from a map by computation or scaling to the actual distance along the center line.
Type: real
Domain: Scale Factor at Center Line > 0.0
Oblique Line Azimuth -- 4.1.2.1.2.11
method used to describe the line along which an oblique mercator map projection is centered using the map projection origin and an azimuth. Compound.
Azimuthal Angle -- 4.1.2.1.2.11.1
angle measured clockwise from north, and expressed in degrees.
Type: real
Domain: 0.0 <= Azimuthal Angle < 360.0
Azimuth Measure Point Longitude -- 4.1.2.1.2.11.2
longitude of the map projection origin.
Type: real
Domain: -180.0 <= Azimuth Measure Point Longitude < 180.0
Oblique Line Point -- 4.1.2.1.2.12
method used to describe the line along which an oblique mercator map projection is centered using two points near the limits of the mapped region that define the center line. Compound.
Oblique Line Latitude -- 4.1.2.1.2.12.1
latitude of a point defining the oblique line.
Type: real
Domain: -90.0 <= Oblique Line Latitude <= 90.0
Oblique Line Longitude -- 4.1.2.1.2.12.2
longitude of a point defining the oblique line.
Type: real
Domain: -180.0 <= Oblique Line Longitude < 180.0
Straight Vertical Longitude from Pole -- 4.1.2.1.2.13
longitude to be oriented straight up from the North or South Pole.
Type: real
Domain: -180.0 <= Straight Vertical Longitude from Pole < 180.0
Scale Factor at Projection Origin -- 4.1.2.1.2.14
a multiplier for reducing a distance obtained from a map by computation or scaling to the actual distance at the projection origin.
Type: real
Domain: Scale Factor at Projection Origin > 0.0
Landsat Number -- 4.1.2.1.2.15
number of the Landsat satellite. (Note: This data element exists solely to provide a parameter needed to define the space oblique mercator projection. It is not used to identify data originating from a remote sensing vehicle.)
Type: Integer
Domain: 0 < Landsat Number < 5
Path Number -- 4.1.2.1.2.16
number of the orbit of the Landsat satellite. (Note: This data element exists solely to provide a parameter needed to define the space oblique mercator projection. It is not used to identify data originating from a remote sensing vehicle.)
Type: integer
Domain: 0 < Path Number < 251 for Landsats 1, 2, or 3; 0 < Path Number < 233 for Landsats 4 or 5
Scale Factor at Central Meridian -- 4.1.2.1.2.17
a multiplier for reducing a distance obtained from a map by computation or scaling to the actual distance along the central meridian.
Type: real
Domain: Scale Factor at Central Meridian > 0.0
Other Projection's Definition -- 4.1.2.1.3
a complete description of a projection, not defined elsewhere in this standard, that was used for the data set. The information provided shall include the name of the projection, the names of the parameters and values used for the data set, and the citation of the specification for the algorithms that describe the mathematical relationship between the Earth and the plane or developable surface for the projection.
Type: text
Domain: free text
Grid Coordinate System -- 4.1.2.2
a plane-rectangular coordinate system usually based on, and mathematically adjusted to, a map projection so that geographic positions can be readily transformed to and from plane coordinates. Compound.
Grid Coordinate System Name -- 4.1.2.2.1
name of the grid coordinate system.
Type: text
Domain:
"Universal Transverse Mercator"
"Universal Polar Stereographic"
"State Plane Coordinate System 1927"
"State Plane Coordinate System 1983"
"ARC Coordinate System"
"other grid system"
Universal Transverse Mercator (UTM) -- 4.1.2.2.2
a grid system based on the transverse mercator projection, applied between latitudes 84 degrees north and 80 degrees south on the Earth's surface. Compound.
UTM Zone Number -- 4.1.2.2.2.1
identifier for the UTM zone.
Type: integer
Domain: 1 <= UTM Zone Number <= 60 for the northern hemisphere; -60 <= UTM Zone Number <= -1 for the southern hemisphere
Universal Polar Stereographic (UPS) -- 4.1.2.2.3
a grid system based on the polar stereographic projection, applied to the Earth's polar regions north of 84 degrees north and south of 80 degrees south. Compound.
UPS Zone Identifier -- 4.1.2.2.3.1
identifier for the UPS zone.
Type: text
Domain: "A" "B" "Y" "Z"
State Plane Coordinate System (SPSC) -- 4.1.2.2.4
a plane-rectangular coordinate system established for each state in the United States by the National Geodetic Survey. Compound.
SPCS Zone Identifier -- 4.1.2.2.4.1
identifier for the SPCS zone.
Type: text
Domain: Four-digit numeric codes for the State Plane Coordinate Systems based on the North American Datum of 1927 are found in Department of Commerce, 1986, Representation of geographic point locations for information interchange (Federal Information Processing Standard 70-1): Washington: Department of Commerce, National Institute of Standards and Technology. Codes for the State Plane Coordinate Systems based on the North American Datum of 1983 are found in Department of Commerce, 1989 (January), State Plane Coordinate System of 1983 (National Oceanic and Atmospheric Administration Manual NOS NGS 5): Silver Spring, Maryland, National Oceanic and Atmospheric Administration, National Ocean Service, Coast and Geodetic Survey.
ARC Coordinate System -- 4.1.2.2.5
the Equal Arc-second Coordinate System, a plane-rectangular coordinate system established in Department of Defense, 1990, Military specification ARC Digitized Raster Graphics (ADRG) (MIL-A-89007): Philadelphia, Department of Defense, Defense Printing Service Detachment Office. Compound.
ARC System Zone Identifier -- 4.1.2.2.5.1
identifier for the ARC Coordinate System Zone.
Type: integer
Domain: 1 <= ARC System Zone Identifier <= 18
Other Grid System's Definition -- 4.1.2.2.6
a complete description of a grid system, not defined elsewhere in this standard, that was used for the data set. The information provided shall include the name of the grid system, the names of the parameters and values used for the data set, and the citation of the specification for the algorithms that describe the mathematical relationship between the Earth and the coordinates of the grid system.
Type: text
Domain: free text
Local Planar -- 4.1.2.3
any right-handed planar coordinate system of which the z-axis coincides with a plumb line through the origin that locally is aligned with the surface of the Earth. Compound.
Local Planar Description -- 4.1.2.3.1
a description of the local planar system.
Type: text
Domain: free text
Local Planar Georeference Information -- 4.1.2.3.2
a description of the information provided to register the local planar system to the Earth (e.g. control points, satellite ephemeral data, inertial navigation data).
Type: text
Domain: free text
Planar Coordinate Information -- 4.1.2.4
information about the coordinate system developed on the planar surface. Compound.
Planar Coordinate Encoding Method -- 4.1.2.4.1
the means used to represent horizontal positions.
Type: text
Domain: "coordinate pair" "distance and bearing" "row and column"
Coordinate Representation -- 4.1.2.4.2
the method of encoding the position of a point by measuring its distance from perpendicular reference axes (the "coordinate pair" and "row and column" methods). Compound.
Abscissa Resolution -- 4.1.2.4.2.1
the (nominal) minimum distance between the "x" or column values of two adjacent points, expressed in Planar Distance Units of measure.
Type: real
Domain: Abscissa Resolution > 0.0
Ordinate Resolution -- 4.1.2.4.2.2
the (nominal) minimum distance between the "y" or row values of two adjacent points, expressed in Planar Distance Units of measure.
Type: real
Domain: Ordinate Resolution > 0.0
Distance and Bearing Representation -- 4.1.2.4.3
a method of encoding the position of a point by measuring its distance and direction (azimuth angle) from another point. Compound.
Distance Resolution -- 4.1.2.4.3.1
the minimum distance measurable between two points, expressed Planar Distance Units of measure.
Type: real
Domain: Distance Resolution > 0.0
Bearing Resolution -- 4.1.2.4.3.2
the minimum angle measurable between two points, expressed in Bearing Units of measure.
Type: real
Domain: Bearing Resolution > 0.0
Bearing Units -- 4.1.2.4.3.3
units of measure used for angles.
Type: text
Domain: "Decimal degrees" "Decimal minutes" "Decimal seconds" "Degrees and decimal minutes" "Degrees, minutes, and decimal seconds" "Radians" "Grads"
Bearing Reference Direction -- 4.1.2.4.3.4
direction from which the bearing is measured.
Type: text
Domain: "North" "South"
Bearing Reference Meridian -- 4.1.2.4.3.5
axis from which the bearing is measured.
Type: text
Domain: "Assumed" "Grid" "Magnetic" "Astronomic" "Geodetic"
Planar Distance Units -- 4.1.2.4.4
units of measure used for distances.
Type: text
Domain: "meters" "international feet" "survey feet" free text
Local -- 4.1.3
a description of any coordinate system that is not aligned with the surface of the Earth. Compound.
Local Description -- 4.1.3.1
a description of the coordinate system and its orientation to the surface of the Earth.
Type: text
Domain: free text
Local Georeference Information -- 4.1.3.2
a description of the information provided to register the local system to the Earth (e.g. control points, satellite ephemeral data, inertial navigation data).
Type: text
Domain: free text
Geodetic Model -- 4.1.4
parameters for the shape of the earth. Compound.
Horizontal Datum Name -- 4.1.4.1
the identification given to the reference system used for defining the coordinates of points.
Type: text
Domain: "North American Datum of 1927" "North American Datum of 1983" free text
Ellipsoid Name -- 4.1.4.2
identification given to established representations of the Earth's shape.
Type: text
Domain: "Clarke 1866" "Geodetic Reference System 80" free text
Semi-major Axis -- 4.1.4.3
radius of the equatorial axis of the ellipsoid.
Type: real
Domain: Semi-major Axis > 0.0
Denominator of Flattening Ratio -- 4.1.4.4
the denominator of the ratio of the difference between the equatorial and polar radii of the ellipsoid when the numerator is set to 1.
Type: real
Domain: Denominator of Flattening > 0.0
Vertical Coordinate System Definition -- 4.2
the reference frame or system from which vertical distances (altitudes or depths) are measured. Compound.
Altitude System Definition -- 4.2.1
the reference frame or system from which altitudes (elevations) are measured. The term "altitude"' is used instead of the common term "elevation" to conform to the terminology in Federal Information Processing Standards 70-1 and 173. Compound.
Altitude Datum Name -- 4.2.1.1
the identification given to the level surface taken as the surface of reference from which altitudes are measured.
Type: text
Domain: "National Geodetic Vertical Datum of 1929" "North American Vertical Datum of 1988" free text
Altitude Resolution -- 4.2.1.2
the minimum distance possible between two adjacent altitude values, expressed in Altitude Distance Units of measure.
Type: real
Domain: Altitude Resolution > 0.0
Altitude Distance Units -- 4.2.1.3
units in which altitudes are recorded.
Type: text
Domain: "meters" "feet" free text
Altitude Encoding Method -- 4.2.1.4
the means used to encode the altitudes.
Type: text
Domain: "Explicit elevation coordinate included with horizontal coordinates" "Implicit coordinate" "Attribute values"
Depth System Definition -- 4.2.2
the reference frame or system from which depths are measured. Compound.
Depth Datum Name -- 4.2.2.1
the identification given to surface of reference from which depths are measured.
Type: text
Domain:
"Local surface"
"Chart datum; datum for sounding reduction"
"Lowest astronomical tide"
"Highest astronomical tide"
"Mean low water"
"Mean high water"
"Mean sea level"
"Land survey datum"
"Mean low water springs"
"Mean high water springs"
"Mean low water neap"
"Mean high water neap"
"Mean lower low water"
"Mean lower low water springs"
"Mean higher high water"
"Mean higher low water"
"Mean lower high water"
"Spring tide"
"Tropic lower low water"
"Neap tide"
"High water"
"Higher high water"
"Low water"
"Low-water datum"
"Lowest low water"
"Lower low water"
"Lowest normal low water"
"Mean tide level"
"Indian spring low water"
"High-water full and charge"
"Low-water full and charge"
"Columbia River datum"
"Gulf Coast low water datum"
"Equatorial springs low water"
"Approximate lowest astronomical tide"
"No correction"
free text
Depth Resolution -- 4.2.2.2
the minimum distance possible between two adjacent depth values, expressed in Depth Distance Units of measure.
Type: real
Domain: Depth Resolution > 0.0
Depth Distance Units -- 4.2.2.3
units in which depths are recorded.
Type: text
Domain: "meters" "feet" free text
Depth Encoding Method -- 4.2.2.4
the means used to encode depths.
Type: text
Domain: "Explicit depth coordinate included with horizontal coordinates" "Implicit coordinate" "Attribute values"
June 8, 1994