4 : Spatial Reference Information

Spatial Reference Information -- the description of the reference frame for, and the means to encode, coordinates in the data set.
Type: compound
Short Name: spref

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 |
Map_Projection_Parameters]

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_Perspective =
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

Map_Projection_Parameters =
Appropriate data elements 4.1.2.1.23.1 through 4.1.2.1.23.18 to
document the map projection parameters.

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

4.1 Horizontal Coordinate System Definition -- the reference frame or system from which linear or angular quantities are measured and assigned to the position that a point occupies.
Type: compound
Short Name: horizsys

4.1.1 Geographic -- the quantities of latitude and longitude which define the position of a point on the Earth's surface with respect to a reference spheroid.
Type: compound
Short Name: geograph

4.1.1.1 Latitude Resolution -- the minimum difference between two adjacent latitude values expressed in Geographic Coordinate Units of measure.
Type: real
Domain: Latitude Resolution > 0.0
Short Name: latres

4.1.1.2 Longitude Resolution -- the minimum difference between two adjacent longitude values expressed in Geographic Coordinate Units of measure.
Type: real
Domain: Longitude Resolution > 0.0
Short Name: longres

4.1.1.3 Geographic Coordinate Units -- 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"
Short Name: geogunit

4.1.2 Planar -- 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.
Type: compound
Short Name: planar

4.1.2.1 Map Projection -- the systematic representation of all or part of the surface of the Earth on a plane or developable surface.
Type: compound
Short Name: mapproj

4.1.2.1.1 Map Projection Name -- 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" free text
Short Name: mapprojn

4.1.2.1.2 Albers Conical Equal Area -- contains parameters for the Albers Conical Equal Area projection.
Type: compound
Short Name: albers

4.1.2.1.3 Azimuthal Equidistant -- contains parameters for the Azimuthal Equidistant projection.
Type: compound
Short Name:azimequi

4.1.2.1.4 Equidistant Conic -- contains parameters for the Equidistant Conic projection.
Type: compound
Short Name: equicon

4.1.2.1.5 Equirectangular -- contains parameters for the Equirectangular projection.
Type: compound
Short Name: equirect

4.1.2.1.6 General Vertical Near-sided Perspective -- contains parameters for the General Vertical Near-sided Perspective projection.
Type: compound
Short Name: gvnsp

4.1.2.1.7 Gnomonic -- contains parameters for the Gnomonic projection.
Type: compound
Short Name: gnomonic

4.1.2.1.8 Lambert Azimuthal Equal Area -- contains parameters for the Lambert Azimuthal Equal Area projection.
Type: compound
Short Name: lamberta

4.1.2.1.9 Lambert Conformal Conic -- contains parameters for the Lambert Conformal Conic projection.
Type: compound
Short Name:lambertc

4.1.2.1.10 Mercator -- contains parameters for the Mercator projection
Type: compound
Short Name: mercator

4.1.2.1.11 Modified Stereographic for Alaska -- contains parameters for the Modified Stereographic for Alaska projection.
Type: compound
Short Name: modsak

4.1.2.1.12 Miller Cylindrical -- contains parameters for the Miller Cylindrical projection.
Type: compound
Short Name: miller

4.1.2.1.13 Oblique Mercator -- contains parameters for the Oblique Mercator projection.
Type: compound
Short Name: obqmerc

4.1.2.1.14 Orthographic -- contains parameters for the Orthographic projection.
Type: compound
Short Name:orthogr

4.1.2.1.15 Polar Stereographic -- contains parameters for the Polar Stereographic projection.
Type: compound
Short Name:polarst

4.1.2.1.16 Polyconic -- contains parameters for the Polyconic projection.
Type: compound
Short Name:polycon

4.1.2.1.17 Robinson -- contains parameters for the Robinson projection.
Type: compound
Short Name: robinson

4.1.2.1.18 Sinusoidal -- contains parameters for the Sinusoidal projection.
Type: compound
Short Name: sinusoid

4.1.2.1.19 Space Oblique Mercator (Landsat) -- contains parameters for the Space Oblique Mercator (Landsat) projection.
Type: compound
Short Name: spaceobq

4.1.2.1.20 Stereographic -- contains parameters for the Stereographic projection.
Type: compound
Short Name: stereo

4.1.2.1.21 Transverse Mercator -- contains parameters for theTransverse mercator projection.
Type: compound
Short Name: transmer

4.1.2.1.22 van der Grinten -- contains parameters for the van der Grinten projection.
Type: compound
Short Name: vdgrin

4.1.2.1.23 Map Projection Parameters -- a complete parameter set of the projection that was used for the data set. The information provided shall include the names of the parameters and values used for the data set that describe the mathematical relationship between the Earth and the plane or developable surface for the projection.
Type: compound

4.1.2.1.23.1 Standard Parallel -- 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
Short Name: stdparll

4.1.2.1.23.2 Longitude of Central Meridian -- 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
Short Name: longcm

4.1.2.1.23.3 Latitude of Projection Origin -- latitude chosen as the origin of rectangular coordinates for a map projection.
Type: real
Domain: -90.0 <= Latitude of Projection Origin <= 90.0
Short Name: latprjo

4.1.2.1.23.4 False Easting -- 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
Short Name: feast

4.1.2.1.23.5 False Northing -- 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
Short Name: fnorth

4.1.2.1.23.6 Scale Factor at Equator -- 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
Short Name: sfequat

4.1.2.1.23.7 Height of Perspective Point Above Surface -- height of viewpoint above the Earth, expressed in meters.
Type: real
Domain: Height of Perspective Point Above Surface > 0.0
Short Name: heightpt

4.1.2.1.23.8 Longitude of Projection Center -- longitude of the point of projection for azimuthal projections.
Type: real
Domain: -180.0 <= Longitude of Projection Center < 180.0
Short Name: longpc

4.1.2.1.23.9 Latitude of Projection Center -- latitude of the point of projection for azimuthal projections.
Type: real
Domain: -90.0 <= Latitude of Projection Center <= 90.0
Short Name: latprjc

4.1.2.1.23.10 Scale Factor at Center Line -- 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
Short Name: sfctrlin

4.1.2.1.23.11 Oblique Line Azimuth -- method used to describe the line along which an oblique mercator map projection is centered using the map projection origin and an azimuth.
Type: compound
Short Name: obqlazim

4.1.2.1.23.11.1 Azimuthal Angle -- angle measured clockwise from north, and expressed in degrees.
Type: real
Domain: 0.0 <= Azimuthal Angle < 360.0
Short Name: azimangl

4.1.2.1.23.11.2 Azimuth Measure Point Longitude -- longitude of the map projection origin.
Type: real
Domain: -180.0 <= Azimuth Measure Point Longitude < 180.0
Short Name: azimptl

4.1.2.1.23.12 Oblique Line Point -- 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.
Type: compound
Short Name: obqlpt

4.1.2.1.23.12.1 Oblique Line Latitude -- latitude of a point defining the oblique line.
Type: real
Domain: -90.0 <= Oblique Line Latitude <= 90.0
Short Name: obqllat

4.1.2.1.23.12.2 Oblique Line Longitude -- longitude of a point defining the oblique line.
Type: real
Domain: -180.0 <= Oblique Line Longitude < 180.0
Short Name: obqllong

4.1.2.1.23.13 Straight Vertical Longitude from Pole -- longitude to be oriented straight up from the North or South Pole.
Type: real
Domain: -180.0 <= Straight Vertical Longitude from Pole < 180.0
Short Name: svlong

4.1.2.1.23.14 Scale Factor at Projection Origin -- 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
Short Name: sfprjorg

4.1.2.1.23.15 Landsat Number -- 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: free integer
Short Name: landsat

4.1.2.1.23.16 Path Number -- 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, free integer
Short Name: pathnum

4.1.2.1.23.17 Scale Factor at Central Meridian -- 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
Short Name: sfctrmer

4.1.2.1.23.18 Other Projection's Definition -- a description of a projection, not defined elsewhere in the standard, that was used for the data set. The information provided shall include the name of the projection, names of parameters and values used for the data set, and the citation of the specification for the algorithms that describe the mathematical relationship between Earth and plane or developable surface for the projection.
Type: text
Domain: free text

4.1.2.2 Grid Coordinate System -- 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.
Type: compound
Short Name gridsys

4.1.2.2.1 Grid Coordinate System Name -- 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"
Short Name: gridsysn

4.1.2.2.2 Universal Transverse Mercator (UTM) -- a grid system based on the transverse mercator projection, applied between latitudes 84 degrees north and 80 degrees south on the Earth's surface.
Type: compound
Short Name: utm

4.1.2.2.2.1 UTM Zone Number -- 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
Short Name: utmzone

4.1.2.2.3 Universal Polar Stereographic (UPS) -- 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.
Type: compound
Short Name: ups

4.1.2.2.3.1 UPS Zone Identifier -- identifier for the UPS zone.
Type: text
Domain: "A" "B" "Y" "Z"
Short Name: upszone

4.1.2.2.4 State Plane Coordinate System (SPCS) -- a plane-rectangular coordinate system established for each state in the United States by the National Geodetic Survey.
Type: compound
Short Name: spcs

4.1.2.2.4.1 SPCS Zone Identifier -- 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.
Short Name: spcszone

4.1.2.2.5 ARC Coordinate System -- 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.
Type: compound
Short Name: arcsys

4.1.2.2.5.1 ARC System Zone Identifier -- identifier for the ARC Coordinate System Zone.
Type: integer
Domain: 1 <= ARC System Zone Identifier <= 18
Short Name: arczone

4.1.2.2.6 Other Grid System's Definition -- 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
Short Name: othergrd

4.1.2.3 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.
Type: compound
Short Name: localp

4.1.2.3.1 Local Planar Description -- a description of the local planar system.
Type: text
Domain: free text
Short Name: localpd

4.1.2.3.2 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).
Type: text
Domain: free text
Short Name: localpgi

4.1.2.4 Planar Coordinate Information -- information about the coordinate system developed on the planar surface.
Type: compound
Short Name: planci

4.1.2.4.1 Planar Coordinate Encoding Method -- the means used to represent horizontal positions.
Type: text
Domain: "coordinate pair" "distance and bearing" "row and column"
Short Name: plance

4.1.2.4.2 Coordinate Representation -- 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).
Type: compound
Short Name: coordrep

4.1.2.4.2.1 Abscissa Resolution -- 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
Short Name: absres

4.1.2.4.2.2 Ordinate Resolution -- 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
Short Name: ordres

4.1.2.4.3 Distance and Bearing Representation -- a method of encoding the position of a point by measuring its distance and direction (azimuth angle) from another point.
Type: compound
Short Name: distbrep

4.1.2.4.3.1 Distance Resolution -- the minimum distance measurable between two points, expressed Planar Distance Units of measure.
Type: real
Domain: Distance Resolution > 0.0
Short Name: distres

4.1.2.4.3.2 Bearing Resolution -- the minimum angle measurable between two points, expressed in Bearing Units of measure.
Type: real
Domain: Bearing Resolution > 0.0
Short Name: bearres

4.1.2.4.3.3 Bearing Units -- 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"
Short Name: bearunit

4.1.2.4.3.4 Bearing Reference Direction -- direction from which the bearing is measured.
Type: text
Domain: "North" "South"
Short Name: bearrefd

4.1.2.4.3.5 Bearing Reference Meridian -- axis from which the bearing is measured.
Type: text
Domain: "Assumed" "Grid" "Magnetic" "Astronomic" "Geodetic"
Short Name: bearrefm

4.1.2.4.4 Planar Distance Units -- units of measure used for distances.
Type: text
Domain: "meters" "international feet" "survey feet" free text
Short Name: plandu

4.1.3 Local -- a description of any coordinate system that is not aligned with the surface of the Earth.
Type: compound
Short Name: local

4.1.3.1 Local Description -- a description of the coordinate system and its orientation to the surface of the Earth.
Type: text
Domain: free text
Short Name: localdes

4.1.3.2 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).
Type: text
Domain: free text
Short Name: localgeo

4.1.4 Geodetic Model -- parameters for the shape of the earth.
Type: compound
Short Name: geodetic

4.1.4.1 Horizontal Datum Name -- 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
Short Name: horizdn

4.1.4.2 Ellipsoid Name -- identification given to established representations of the Earth's shape.
Type: text
Domain: "Clarke 1866" "Geodetic Reference System 80" free text
Short Name: ellips

4.1.4.3 Semi-major Axis -- radius of the equatorial axis of the ellipsoid.
Type: real
Domain: Semi-major Axis > 0.0
Short Name: semiaxis

4.1.4.4 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 set to 1.
Type: real
Domain: Denominator of Flattening > 0.0
Short Name: denflat

4.2 Vertical Coordinate System Definition -- the reference frame or system from which vertical distances (altitudes or depths) are measured.
Type: compound
Short Name: vertdef

4.2.1 Altitude System Definition -- 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.
Type: compound
Short Name: altsys

4.2.1.1 Altitude Datum Name -- the identification given to the 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
Short Name: altdatum

4.2.1.2 Altitude Resolution -- the minimum distance possible between two adjacent altitude values, expressed in Altitude Distance Units of measure.
Type: real
Domain: Altitude Resolution > 0.0
Short Name: altres

4.2.1.3 Altitude Distance Units -- units in which altitudes are recorded.
Type: text
Domain: "meters" "feet" free text
Short Name: altunits

4.2.1.4 Altitude Encoding Method -- the means used to encode the altitudes.
Type: text
Domain: "Explicit elevation coordinate included with horizontal coordinates" "Implicit coordinate" "Attribute values"
Short Name: altenc

4.2.2 Depth System Definition -- the reference frame or system from which depths are measured.
Type: compound
Short Name: depthsys

4.2.2.1 Depth Datum Name -- 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
Short Name: depthdn

4.2.2.2 Depth Resolution -- the minimum distance possible between two adjacent depth values, expressed in Depth Distance Units of measure.
Type: real
Domain: Depth Resolution > 0.0
Short Name: depthres

4.2.2.3 Depth Distance Units -- units in which depths are recorded.
Type: text
Domain: "meters" "feet" free text
Short Name: depthdu

4.2.2.4 Depth Encoding Method -- the means used to encode depths.
Type: text
Domain: "Explicit depth coordinate included with horizontal coordinates" "Implicit coordinate" "Attribute values"
Short Name: depthem