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_Nearsided_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_Nearsided_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 =
 StraightVertical_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 +
 Semimajor_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 Nearsided 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 Nearsided Perspective  contains parameters for the General Vertical Nearsided 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 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.
 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 planerectangular 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: Fourdigit 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 701): 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 Arcsecond Coordinate System, a plane rectangular coordinate system established in Department of Defense, 1990, Military specification ARC Digitized Raster Graphics (ADRG) (MILA89007): 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 righthanded planar coordinate system of which the zaxis 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 Semimajor Axis  radius of the equatorial axis of the ellipsoid.
 Type: real
 Domain: Semimajor 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 701 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" "Lowwater datum" "Lowest low water" "Lower low water" "Lowest normal low water" "Mean tide level" "Indian spring low water" "Highwater full and charge" "Lowwater 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