342 - Geospatial Reference Data (R)
MARC 21 Bibliographic - Full
February 1999
First Indicator
Geospatial reference dimension
0 - Horizontal coordinate system
1 - Vertical coordinate system
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Second Indicator
Geospatial reference method
0 - Geographic
1 - Map projection
2 - Grid coordinate system
3 - Local planar
4 - Local
5 - Geodetic model
6 - Altitude
7 - Method specified in $2
8 - Depth
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Subfield Codes
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$a - Name (NR)
$b - Coordinate units or distance units (NR)
$c - Latitude resolution (NR)
$d - Longitude resolution (NR)
$e - Standard parallel or oblique line latitude (R)
$f - Oblique line longitude (R)
$g - Longitude of central meridian or projection center (NR)
$h - Latitude of projection center or projection origin (NR)
$i - False easting (NR)
$j - False northing (NR)
$k - Scale factor (NR)
$l - Height of perspective point above surface (NR)
$m - Azimuthal angle (NR)
$n - Azimuth measure point longitude or straight vertical longitude from pole (NR)
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$o - Landsat number and path number (NR)
$p - Zone identifier (NR)
$q - Ellipsoid name (NR)
$r - Semi-major axis (NR)
$s - Denominator of flattening ratio (NR)
$t - Vertical resolution (NR)
$u - Vertical encoding method (NR)
$v - Local planar, local, or other projection or grid description (NR)
$w - Local planar or local georeference information (NR)
$2 - Reference method used (NR)
$6 - Linkage (NR)
$8 - Field link and sequence number (R)
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FIELD DEFINITION AND SCOPE
Description of the frame of reference for the coordinates in a data set. To work with a
data set a user must be able to identify how location accuracy has been affected through
the application of a geospatial reference method, thus enabling the user to manipulate
the data set to recover location accuracy.
GUIDELINES FOR APPLYING CONTENT DESIGNATORS
■ INDICATORS
First Indicator - Geospatial reference dimension Whether the system used measures linear or angular quantities or measures vertical
distances (altitudes or depths).
0 - Horizontal coordinate system System which measures linear or angular distances.
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01$aPolyconic$g0.9996$h0$i500,000$j0
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1 - Vertical coordinate system System which measures vertical distances (altitudes or depths).
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16$aNational geodetic vertical datum of 1929$v1$bmeters$wImplicit coordinates.
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Second Indicator - Geospatial reference method Method used to identify the system.
0 - Geographic Coordinate system which defines the position of a point on the Earth's surface
with respect to a reference spheroid.
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00$c0.0004$d0.0004$bDecimal degrees
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1 - Map projection Systematic representation of all or part of the surface of the Earth on a
plane.
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01$aPolyconic$g0.9996$h0$i500,000$j0
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2 - Grid coordinate system 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.
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02$aUniversal transverse Mercator
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3 - Local planar Any right-handed planar coordinate system of which the z-axis coincides with a
plumb line through the origin that locally is aligned with the surface of the
Earth.
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03$aNorth American datum of 1927
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4 - Local Any coordinate system that is not aligned with the surface of the Earth.
5 - Geodetic model Parameters for the shape of the Earth.
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05$sWorld geodetic system 72$t6378135$u298.26
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6 - Altitude System which measures altitudes (elevations).
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16$aNational geodetic vertical datum of 1929$v1$bmeters$wImplicit coordinates.
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7 - Method specified in $2 Geospatial reference method used in the data set is specified in subfield
$2.
8 - Depth System which measures depths.
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18$aLowest astronomical tide
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■ SUBFIELD CODES
$a - Name Name of a map projection when the second indicator contains value 1. The map
projection is also coded in field 008/22-23 (Projection).
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01$aAlbers conical equal area
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Used for the name of the grid coordinate system when the second indicator has
value 2.
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02$aUniversal transverse Mercator
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Used for a horizontal datum name (the system used for defining the coordinates of
points) when the second indicator has value 5.
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05$aNorth American datum of 1927
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Used for an altitude datum name (the level surface from which altitudes are
measured) when the second indicator has value 6.
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16$aNational geodetic vertical datum
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Used for a depth datum name (the surface from which depths are measured) when the
second indicator has value 8.
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| 342 |
18$aLowest astronomical tide
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$b - Coordinate units or distance units Geographic coordinate units (units of measure used for latitude and longitude
values) when the second indicator has value 0. Contains altitude distance units
(units in which altitudes are recorded) when the second indicator has value 6 and
depth distance units (units in which depths are recorded) when the second
indicator has value 8.
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16$aNational geodetic vertical datum of 1929$v1$bmeters$wImplicit coordinates.
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$c - Latitude resolution Minimum difference between two adjacent latitude values expressed in geographic
coordinate units of measure.
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00$c0.0004$d0.0004$bDecimal degrees
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$d - Longitude resolution Minimum difference between two adjacent longitude values expressed in geographic
coordinate units of measure.
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05$aWorld Geodetic System 1984 (WGS-84)$c0.0000001$d0.0000001$bDegrees, Minutes, and Decimal seconds$qWorld Geodetic System 1984 (WGS-84)$r6378137.0$s298.257223563
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$e - Standard parallel or oblique line latitude Standard parallel(s) (line of constant latitude at which the surface of the Earth
and the plane intersect) when the second indicator contains the value 1 and
$a contains the text Albers conical equal area,
Equidistant conic, Equirectangular, Lambert conformal
conic, Mercator, or Polar stereographic. Contains
oblique line latitude(s) (latitude of a point defining the line along which the
projection is centered) when the second indicator contains the value 1 and
$a contains the text Oblique Mercator.
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01$aLambert conformal conic$e38.3$e39.45$g-77$h37.8333$i800,000$j0
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$f - Oblique line longitude Longitude(s) of a point defining the line along which the Oblique Mercator
projection is centered.
$g - Longitude of central meridian or projection center 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) when the
second indicator contains the value 1 and subfield $a contains the text
Albers conical equal area, Azimuthal equidistant,
Equidistant conic, Equirectangular, Lambert conformal
conic, Mercator, Miller cylindrical, Polyconic,
Sinusoidal, Transverse Mercator, or Van der Grinten.
Subfield $g contains a longitude of projection center (longitude of the
point of projection for azimuthal projections) when the second indicator contains
the value 1 and subfield $a contains the text General vertical
near-sided projection, Gnomomic, Lambert azimuthal equal
area, Orthographic, Robinson, or
Stereographic.
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01$aPolyconic$g0.9996$h0$i500,000$j0
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$h - Latitude of projection center or projection origin Latitude of projection center (latitude of the point of projection for azimuthal
projections) when the second indicator contains the value 1 and subfield
$a contains the text General vertical near-sided projection,
Gnomomic, Orthographic, or Stereographic. Subfield
$h contains a latitude of projection origin (latitude chosen as the
origin of rectangular coordinates for a map projection) when subfield
$a contains the text Albers conical equal area, Azimuthal
equidistant, Equidistant conic, Lambert conformal conic,
Oblique Mercator, Polyconic, or Transverse
Mercator.
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| 342 |
02$aUniversal Transverse Mercator$p13$k0.9996$g-105.00$h0.00$i500,000$j0.0
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$i - False easting Value added to all x values in the rectangular coordinates for a map
projection.
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| 342 |
02$aState Plane Coordinate System 27, Lambert Conformal
Conic$p0405$g-69.0$h0.0$i500000.0$j0.0
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$j - False northing Value added to all y values in the rectangular coordinates for a map
projection.
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| 342 |
01$aPolyconic$g0.9996$h0$i500,000$j0
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$k - Scale factor Used when the first indicator contains the value 1. If subfield $a
contains the text Mercator, subfield $k contains the scale
factor at equator (a multiplier for reducing a distance obtained from a map to the
actual distance along the equator). If subfield $a contains Oblique
Mercator, subfield $k contains the scale factor at center line
(a multiplier for reducing a distance obtained from a map to the actual distance
along the center line). If subfield $a contains Transverse
Mercator, subfield $k contains the scale factor at central
meridian (a multiplier for reducing a distance obtained from a map to the actual
distance along the central meridian). If subfield $a contains Polar
stereographic, subfield $k contains the scale factor at the
projection origin (a multiplier for reducing a distance obtained from a map to the
actual distance at the projection origin).
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12$aUniversal Transverse Mercator$p13$k0.9996$g-105.00$h0.00$i500,000$j0.0
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$l - Height of perspective point above surface Height of the viewpoint above the Earth, expressed in meters, for the General
vertical near-sided projection.
$m - Azimuthal angle Angle measured clockwise from north, and expressed in degrees when $a
contains the text Oblique Mercator.
$n - Azimuth measure point longitude or straight vertical longitude from pole Azimuth measure point longitude (longitude of the map projection origin) when
subfield $a contains the text Oblique Mercator. It contains a
straight vertical longitude from pole (a longitude to be oriented straight up from
the North or South Pole) when $a contains Polar
stereographic.
$o - Landsat number and path number Identification number of the Landsat satellite and the path number for the Space
oblique Mercator projection.
$p - Zone identifier Used for the zone identifier for the grid coordinate system identified in subfield
$a.
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02$aState Plane Coordinate System 27, Lambert Conformal
Conic$p0405$g-69.0$h0.0$i500000.0$j0.0
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$q - Ellipsoid name Identification given to an established representation of the Earth’s shape.
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02$aNorth American Datum of 1927$qClarke 1866$r6378206.4$s294.98
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$r - Semi-major axis Radius of the equatorial axis of the ellipsoid.
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03$vMissouri East State Plane NAD27$qClarke 1866$r6378206.4 M$s294.97869821
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$s - Denominator of flattening ratio Denominator of the ratio of the difference between the equatorial and polar radii
of the ellipsoid when the numerator is set to 1.
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05$sWorld geodetic system 72$t6378135$u298.26
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$t - Vertical resolution Altitude resolution (the minimum distance possible between two adjacent altitude
values, expressed in altitude distance units of measure) when the second indicator
contains the value 6. When the second indicator contains the value 8, subfield
$t contains the depth resolution (the minimum distance possible between
two adjacent depth values, expressed in depth distance units of measure).
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06$sWorld geodetic system 72$t6378135$u298.26
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$u - Vertical encoding method Altitude encoding method when the second indicator contains the value 6. When the
second indicator contains the value 8, subfield $u contains the depth
encoding method.
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18$aNGVD 1929$t0.01$bfeet$uExplicit depth coordinate included with horizontal
coordinates
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$v - Local planar, local, or other projection or grid description Local planar system (any right-handed planar coordinate system of which the
z-axis coincides with a plumb line through the origin that is aligned
locally with the surface of the Earth) when the second indicator has value 3.
Subfield $v contains a 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) when the second indicator has value 4.
Subfield $v contains a complete description for an undefined projection
used for the data set. The information provided includes 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 when the second
indicator has value 1.
Subfield $v contains a complete description for an undefined grid
system used for the data set. The information provided includes 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 when the
second indicator has value 2.
$w - Local planar or local georeference information Local planar georeference information (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)) when the second indicator has value 3.
Subfield $w contains local georeference information (a description of
the information provided to register the local system to the Earth (e.g. control
points, satellite ephemeral data, inertial navigation data)) when the second
indicator has value 4.
$2 - Reference method used Geospatial reference method used in the data set when the second indicator
contains value 7.
$8 - Field link and sequence number
INPUT CONVENTIONS
Data Constant - May be used in conjunction with the U.S. Federal Geographic Data Committee’s
Content
Standards for Digital Geospatial Metadata (FGDC-STD-001) (
www.fgdc.gov) and related standards developed by
ISO/TC211.
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 equal-area map. Sizes of
areas are distorted on conformal maps 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 north-south in extent, others for large areas that are mainly east-west in
extent, and still others for large areas that are oblique to the Equator.
The subfields used in field 342 for each map projection are identified as follows.
| Projection |
Subfields used |
| Albers conical equal area |
$a,$e,$g,$h,$i,$j |
| Azimuthal equidistant |
$a,$g,$h,$i,$j |
| Equidistant conic |
$a,$e,$g,$h,$i,$j |
| Equirectangular |
$a,$e,$g,$i,$j |
| General vertical near-sided perspective |
$a,$l,$g,$h,$i,$j |
| Gnomonic |
$a,$g,$h,$i,$j |
| Lambert azimuthal equal area |
$a,$g,$h,$i,$j |
| Lambert conformal conic |
$a,$e,$g,$h,$i,$j |
| Mercator |
$a,$e or
$k,$g,$i,$j |
| Miller cylindrical |
$a, $g, $i,
$j |
| Modified stereographic for Alaska |
$a,$i,$j,$a,$g,$i,$j |
| Oblique Mercator |
$a,$k,$m
and $n or $e$f$e$f,$h,$i,$j |
| Orthographic |
$a,$g,$h,$i,$j |
| Polar stereographic |
$a,$n,$e
or
$k,$i,$j |
| Polyconic |
$a,$g,$h,$i,$j |
| Robinson |
$a,$g,$i,$j |
| Sinusoidal |
$a,$g,$i,$j |
| Space oblique Mercator |
$a,$o,$i,$j |
| Stereographic |
$a,$g,$h,$i,$j |
| Transverse Mercator |
$a,$k,$g,$h,$i,$j |
| Van der Grinten |
$a,$g,$i,$j |
Punctuation - Field 342 does not end with a period, unless the last word in the field is an
abbreviation.