Definition 
Description of the frame of reference for the coordinates in a data set. Include enough information so that the user can identify how location accuracy has been affected through the application of a geospatial reference method, and can manipulate the data set to recover location accuracy. May be used in conjunction with the Content Standards for Digital Geospatial Metadata available at the Federal Geographic Data Committee web site (http://www.fgdc.gov/standards/standards_publications/) and related standards developed by ISO/TC211. 
Guidelines 

Map projections 
Every flat map misrepresents the surface of the Earth in some way. A map or parts of a map can show one or more—but never all—of the following: true directions, true distances, true areas, true shapes. On an equidistant map, distances are true only along particular lines, such as those radiating from a single point selected as the center of the projection. Shapes are more or less distorted on every equalarea map. On conformal maps, sizes of areas are distorted even though shapes of small areas are shown correctly. The degree and kinds of distortion vary with the projection used in making a map of a particular area. Some projections are suited for mapping large areas that are mainly northsouth in extent, others for large areas that are mainly eastwest in extent, and still others for large areas that are oblique to the Equator. Code the map projection in Proj. Use the following subfields for the designated projection:
Projection 
Subfields 
Albers conical equal area 
ǂa, ǂe, ǂg, ǂh, ǂi, ǂj 
Azimuthal equidistant 
ǂa, ǂg, ǂh, ǂi, ǂj 
Equidistant conic 
ǂa, ǂe, ǂg, ǂh, ǂi, ǂj 
Equirectangular 
ǂa, ǂe, ǂg, ǂi, ǂj 
General vertical nearsided perspective 
ǂa, ǂg, ǂh, ǂi, ǂj, ǂl 
Gnomonic 
ǂa, ǂg, ǂh, ǂi, ǂj 
Lambert azimuthal equal area 
ǂa, ǂg, ǂh, ǂi, ǂj 
Lambert conformal conic 
ǂa, ǂe, ǂg, ǂh, ǂi, ǂj 
Mercator 
ǂa, ǂe , ǂg, ǂi, ǂj, ǂk 
Miller cylindrical 
ǂa, ǂg, ǂi, ǂj 
Modified stereographic for Alaska 
ǂa, ǂi, ǂj 
Oblique Mercator 
ǂa, ǂk, ǂm, ǂn or ǂa, ǂe, ǂf, ǂh, ǂi, ǂj 
Orthographic 
ǂa, ǂg, ǂh, ǂi, ǂj 
Polar stereographic 
ǂa, ǂe, ǂn or ǂa, ǂi, ǂj, ǂk 
Polyconic 
ǂa, ǂg, ǂh, ǂi, ǂj 
Robinson 
ǂa, ǂg, ǂi, ǂj 
Sinusoidal 
ǂa, ǂg, ǂi, ǂj 
Space oblique Mercator 
ǂa, ǂi, ǂj, ǂo 
Stereographic 
ǂa, ǂg, ǂh, ǂi, ǂj 
Transverse Mercator 
ǂa, ǂg, ǂh, ǂi, ǂj, ǂk 
Van der Grinten 
ǂa, ǂg, ǂi, ǂj 

1st Indicator 
Geospatial reference dimension. Indicate a system which measures linear or angular quantities or a system which measures vertical distances (altitudes or depths). 

0 
Horizontal coordinate system. A system that measures linear or angular distances.
342 
0 
1 
Polyconic ǂg 0.9996 ǂh 0 ǂi 500,000 ǂj 0 



1 
Vertical coordinate system. A system that measures vertical distances (altitudes or depths).
342 
1 
6 
National geodetic vertical datum of 1929 ǂv 1 ǂb meters ǂw Implicit coordinates 


2nd Indicator 
Geospatial reference method. Indicates the method used to identify the system. 

0 
Geographic. A coordinate system that defines the position of a point on the Earth's surface with respect to a reference spheroid.
342 
0 
0 
ǂc 0.0004 ǂd 0.0004 ǂb Decimal degrees 



1 
Map projection. A systematic representation of all or part of the surface of the Earth on a plane.
342 
0 
1 
Polyconic ǂg 0.9996 ǂh 0 ǂi 500,000 ǂj 0 



2 
Grid coordinate system. A planerectangular 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.
342 
0 
2 
Map grid of Australia (MGA94) 



3 
Local planar. Any righthanded planar coordinate system of which the zaxis coincides with a plumb line through the origin that is aligned locally with the surface of the Earth.
342 
0 
3 
North American datum of 1927 



4 
Local. Any coordinate system that is not aligned with the surface of the Earth.
342 
0 
4 
ǂv Local Cartesian Projection 



5 
Geodetic model. Parameters for the shape of the Earth.
342 
0 
5 
North American Datum of 1983 ǂq Geodetic Reference System 80 ǂr 6378137.0 ǂs 298.257222 



6 
Altitude. A system which measures altitudes (elevations).
342 
1 
6 
North American Vertical Datum of 1988 ǂt 0.01 ǂb feet ǂu attribute values 



7 
Method specified in ǂ2 . The geospatial reference method used in the data set is specified in subfield ǂ2. Because no heading and term source codes have been defined for use in field 342, it is unlikely that 2nd indicator value 7 and subfield ǂ2 would be used in current cataloging. 


8 
Depth. A system that measures depths.
342 
1 
8 
Lowest astronomical tide 


Subfields 

ǂa Name 
Base the content on the 2nd indicator value.
If 2nd indicator is 
Use subfield ǂa for 
1 
Name of a map projection. The map projection is also coded in Proj 
2 
Grid coordinate system 
5 
Horizontal datum name (the system used for defining the coordinates of points) 
6 
Altitude datum name (the level surface from which altitudes are measured) 
8 
Depth datum name (the surface from which depths are measured 
342 
0 
1 
Albers conical equal area 
342 
0 
2 
Universal transverse Mercator 
342 
0 
5 
North American datum of 1927 
342 
1 
6 
National geodetic vertical datum 
342 
1 
8 
Lowest astronomical tide 

ǂb Coordinate or distance units 
Base the content on the 2nd indicator value.
If 2nd indicator is 
Use subfield ǂb for 
0 
Geographic coordinate units (units of measure used for latitude and longitude values) 
6 
Altitude distance units (units in which altitudes are recorded) 
8 
Depth distance units (units in which depths are recorded) 
342 
0 
0 
ǂc 0.02 ǂd 0.02 ǂb decimal degrees 
342 
1 
6 
North American Datum 1927 ǂv 30 ǂb meters 
342 
1 
8 
NGVD 1929 ǂt 0.01 ǂb feet ǂu explicit depth coordinate included with the horizontal coordinates 

ǂc Latitude resolution 
The minimum difference between two adjacent latitude values expressed in geographic coordinate units of measure.
342 
0 
0 
ǂc 0.0004 ǂd 0.0004 ǂb decimal degrees 

ǂd Longitude resolution 
The minimum difference between two adjacent longitude values expressed in geographic coordinate units of measure.
342 
0 
5 
World Geodetic System 1984 (WGS84) ǂc 0.0000001 ǂd 0.0000001 ǂb degrees, minutes, and decimal seconds ǂq World Geodetic System 1984 (WGS84) ǂr 6378137.0 ǂs 298.257223563 

ǂe Standard parallel or oblique line latitude 
Use when 2nd indicator value is 1. Base the content on subfield ǂa.
If subfield ǂa is 
Use subfield ǂe for 
Albers conical equal area, Equidistant conic, Equirectangular, Lambert conformal conic, Mercator, or Polar stereographic. 
Standard parallels (lines of constant latitude at which the surface of Earth and the plane intersect) 
Oblique Mercator. 
Oblique line latitudes (latitude of a point defining the line along which the projection is centered) 
342 
0 
1 
Lambert conformal conic ǂe 38.3 ǂe 39.45 ǂg 77 ǂh 37.8333 ǂi 800,000 ǂj 0 

ǂf Oblique line longitude 
Longitudes of a point defining the line along which the Oblique Mercator projection is centered.
342 
0 
1 
Oblique Mercator ǂe 41 ǂe 45 ǂf 117 ǂf 120 

ǂg Longitude of central meridian or projection center 
Use when 2nd indicator value is 1. Base the content on subfield ǂa.
If subfield ǂa is 
Use subfield ǂg for 
Albers conical equal area, Azimuthal equidistant, Equidistant conic, Equirectangular, Lambert conformal conic, Mercator, Miller cylindrical, Polyconic, Sinusoidal, Transverse Mercator, or Van der Grinten. 
Longitude of the central meridian (the line of longitude at the center of a map projection, generally used as the basis for constructing the projection) 
General vertical nearsided projection, Gnomonic, Lambert azimuthal equal area, Orthographic, Robinson, or Stereographic. 
Longitude of projection center (longitude of the point of projection for azimuthal projections) 
342 
0 
1 
Polyconic ǂg 0.9996 ǂh 0 ǂi 500,000 ǂj 0 

ǂh Latitude of projection center or projection origin 
Use when 2nd indicator value is 1. Base the content on subfield ǂa.
If subfield ǂa is 
Use subfield ǂh for 
General vertical nearsided projection, Gnomonic, Orthographic, or Stereographic. 
Latitude of projection center (latitude of the point of projection for azimuthal projections) 
Albers conical equal area, Azimuthal equidistant, Equidistant conic, Lambert conformal conic, Oblique Mercator, Polyconic, or Transverse Mercator. 
Latitude of projection origin (latitude chosen as the origin of rectangular coordinates for a map projection) 
342 
0 
1 
Lambert conformal conic ǂe 17.0 ǂg 47.0 ǂh 22.0 ǂi 0.0 ǂj 0.0 ǂq Clarke 1866ǂr 6370997 ǂs 294.98 

ǂi False easting 
The value added to all x values in the rectangular coordinates for a map projection so that none of the values in the geographic region being mapped are negative.
342 
0 
2 
State Plane Coordinate System 27, Lambert Conformal Conic ǂp 0405 ǂg 69.0 ǂh 0.0 ǂi 500,000.0 ǂj 0.0 

ǂj False northing 
The value added to all y values in the rectangular coordinates for a map projection so that none of the values in the geographic region being mapped are negative.
342 
0 
1 
Polyconic ǂg 0.9996 ǂh 0 ǂi 500,000 ǂj 0 

ǂk Scale factor 
In a coordinate system, a value, usually less than one, that converts a tangent projection to a secant projection. Use when the 1st indicator is 1. Base the content on subfield ǂa.
If subfield ǂa is 
Use subfield ǂk for 
Mercator 
Equator (a multiplier for reducing a distance obtained from a map to the actual distance along the equator). 
Oblique Mercator 
Center line (a multiplier for reducing a distance obtained from a map to the actual distance along the center line). 
Transverse Mercator 
Central meridian (a multiplier for reducing a distance obtained from a map to the actual distance along the central meridian). 
Polar stereographic 
The projection origin (a multiplier for reducing a distance obtained from a map to the actual distance at the projection origin). 
342 
1 
2 
Universal transverse Mercator ǂp 13 ǂk 0.9996 ǂg 105.00 ǂh 0.00 ǂi 500,000 ǂj 0.0 

ǂl Height of perspective point above surface 
The height of the viewpoint above the Earth, expressed in meters, for the General vertical nearsided projection.
342 
0 
3 
General Vertical Nearsided Perspective ǂe 43 ǂl 10 ǂg 21 ǂh 44 

ǂm Azimuthal angle 
The angle measured clockwise from north and expressed in degrees when subfield ǂa is Oblique Mercator.
342 
0 
1 
Oblique Mercator ǂm 89.999999 ǂk 1 ǂi 0 ǂj 0 

ǂn Azimuth measure point longitude or straight vertical longitude from pole 
Base the content on subfield ǂa.
342 
0 
1 
Oblique Mercator ǂb meters ǂq GRS80 ǂk 0.9996 ǂg 86.0000 ǂh 45.3092 ǂn 337.25556 ǂi 2546731.496 ǂj 4354009.816 

ǂo Landsat number and path number 
The identification number of the Landsat satellite and the path number for the Space Oblique Mercator projection.
342 
0 
5 
Space Oblique Mercator (Landsat) ǂo Landsat number: 2 ; path number: 142 

ǂp Zone identifier 
A zone identifier for the grid coordinate system identified in subfield ǂa.
342 
0 
2 
State Plane Coordinate System 27, Lambert Conformal Conic ǂp 0405 ǂg 69.0 ǂh 0.0 ǂi 500,000.0 ǂj 0.0 
342 
0 
1 
State Plane Coordinate System 1983 ǂp Zone 5004 

ǂq Ellipsoid name 
An identification given to an established representation of the Earth's shape.
342 
0 
2 
North American Datum of 1927 ǂq Clarke 1866 ǂr 6378206.4 ǂs 294.98 
342 
0 
3 
Altitude datum name: North American Datum of 1983 ǂq ellipsoid name: GRS1980 ǂr semimajor axis: 6378206.4 ǂs denominator of flattening ratio: 294.98 

ǂr Semimajor axis 
The radius of the equatorial axis of the ellipsoid.
342 
0 
3 
ǂv Missouri East State Plane NAD27 ǂq Clarke 1866 ǂr 6378206.4 M ǂs 294.97869821 
342 
0 
3 
Altitude datum name: North American Datum of 1983 ǂq ellipsoid name: GRS1980 ǂr semimajor axis: 6378206.4 ǂs denominator of flattening ratio: 294.98 

ǂs Denominator of flattening ratio 
The denominator of the ratio of the difference between the equatorial and polar radii of the ellipsoid when the numerator is 1.
342 
0 
5 
ǂs 294.98 ǂt 6378135 ǂu 298.26 
342 
0 
3 
Altitude datum name: North American Datum of 1983 ǂq ellipsoid name: GRS1980 ǂr semimajor axis: 6378206.4 ǂs denominator of flattening ratio: 294.98 

ǂt Vertical resolution 
Base the content on 2nd indicator value.
If 2nd indicator is 
Use subfield ǂt for 
6 
Altitude resolution (the minimum distance possible between two adjacent altitude values, expressed in altitude distance units of measure). 
8 
Depth resolution (the minimum distance possible between two adjacent depth values, expressed in depth distance units of measure). 
342 
0 
6 
ǂs 294.98 ǂt 6378135 ǂu 298.26 

ǂu Vertical encoding method 
Base the content on the 2nd indicator value.
If 2nd indicator is 
Use subfield ǂu for 
6 
Altitude encoding method. 
8 
Depth encoding method. 
342 
1 
6 
North American Vertical Datum of 1988 ǂt 0.000010 ǂb meters ǂu Explicit elevation coordinate included with horizontal coordinates 
342 
1 
8 
NGVD 1929 ǂt 0.01 ǂb feet ǂu Explicit depth coordinate included with horizontal coordinates 

ǂv Local planar, local, or other projection or grid description 
Base the content on the 2nd indicator value.
If 2nd indicator is 
Use subfield ǂv for 
1 
Complete description for an undefined projection used for the data set. 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 for the projection. 
2 
Complete description for an undefined grid system used for the data set. 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. 
3 
Description of a local planar system (any righthanded planar coordinate system of which the zaxis coincides with a plumb line through the origin that is aligned locally with the surface of the Earth). 
4 
Description of a local system (any coordinate system that is not aligned with the surface of the Earth and its orientation to the surface of the Earth). 
342 
0 
3 
ǂv Planar System developed by the Engineering Department. Contact Mark Smith with specific questions regarding coordinates. ǂw For instructions on how to georeference the file download the text file "georeference.txt". Specifics can be found in the Cross reference section. 
342 
1 
3 
Universal Transverse Mercator (UTM) ǂq WGS84 ǂv Alvin XY as established 1998, where 0,0 is at 47.dddddd,129.ddddd ǂu Explicit depth coordinate included with horizontal coordinates 
342 
0 
4 
ǂv Local Cartesian Projection 

ǂw Local planar or local georeference information 
Base the content on the 2nd indicator value.
If 2nd indicator is 
Use subfield ǂw for 
3 
Local planar georeference information (a description of the information provided to register the local planar system to the Earth. For example, control points, satellite ephemeral data, inertial navigation data). 
4 
Local georeference information (a description of the information provided to register the local system to the Earth. For example control points, satellite ephemeral data, inertial navigation data). 
342 
0 
3 
ǂv Local planar: coordinates are in Arc/Info form ǂw Local planar georeference information: satellite ephemeral data 

ǂ2 Reference method used 
Use when the 2nd indicator value is 7 for the geospatial reference method used in the data set. Because no heading and term source codes have been defined for use in field 342, it is unlikely that 2nd indicator value 7 and subfield ǂ2 would be used in current cataloging. 
ǂ8 Field link and sequence number 
For information about subfield ǂ8, see Control Subfields. 