]> 2008/06/10 OpenCyc Knowledge Base Copyright© 2001-2008 Cycorp, Inc., http://www.cyc.com/, Austin, TX, USA This file contains an OWL representation of information contained in the OpenCyc Knowledge Base. The content of this OWL file is licensed under the Creative Commons Attribution 3.0 license whose text can be found at http://creativecommons.org/licenses/by/3.0/legalcode. The content of this OWL file, including the OpenCyc content it represents, constitutes the "Work" referred to in the Creative Commons license. The terms of this license equally apply to, without limitation, renamings and other logically equivalent reformulations of the content of this OWL file (or portions thereof) in any natural or formal language, as well as to derivations of this content or inclusion of it in other ontologies. externalID A unique, language-neutral, variable-sized identifier for a concept that can be used to refer unambiguously to that concept across OWL exports or across Cyc inference engines. label A natural-language representation for a concept that is both human readable and readable by the Cyc inference engine. These terms are not guaranteed to refer to the same concept across time but are guaranteed to be consistent within a particular OWL export. Use 'cycAnnot:externalID' for unambiguously referring to a concept across OWL exports or across Cyc inference engines. geodesy concept GeodesyConcept Instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r-4nSRAttEdqAAAACs6hO_g" class="cyc_term">GeodesyConcept</a> are concepts which are included in the domain of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwTnuWZwpEbGdrcN5Y29ycA" class="cyc_term">Geodesy</a>; therefore, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> models of the Earth, map projections, and coordinate systems would be instances of this collection. geodesy concepts the geodesy domain

One of two instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rOGaXOEy0EdqAAAACs6hO_g" class="cyc_term">MagneticPoleOfPlanet</a> found on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a>. The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rObqWcEy0EdqAAAACs6hO_g" class="cyc_term">MagneticNorthPoleOfEarth</a> is the point where the Earth's magnetic field (see #$MagneticFieldOfPlanetEarthFn) points directly down (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViJ65wpEbGdrcN5Y29ycA" class="cyc_term">Down_Directly</a>). Due to the dynamics of the field, the pole is not stationary. MagneticNorthPoleOfEarth the Magnetic North Pole

equatorialRadiusOfSpheroid A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwOSbUJwpEbGdrcN5Y29ycA" class="cyc_term">sizeParameterOfObject</a>. <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a> SPHEROID DISTANCE)</code> means that <code>DISTANCE</code> is one-half the length of <code>SPHEROID</code>'s equatorial axes. Whenever two <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r4BM6CvVqEdmAAAACs0uFOQ" class="cyc_term">symmetricAxes</a> (q.v.) of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> that is not a perfect sphere are of equal length, they are both equatorial axes of the spheroid. All of the equatorial axes of such a spheroid lie in a single plane; the (unique) symmetric-axis of the spheroid that is perpendicular with its equatorial axes is known as its polar axis (cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a>). If a spheroid's equatorial radius is greater than its polar radius, it is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>; if its polar radius is greater than its equatorial radius, it is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a>. The greater radius (whichever it might be) measures the spheroid's semi-major axis (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>). The equatorial and polar radii of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgDAn5wpEbGdrcN5Y29ycA" class="cyc_term">Sphere</a> are both equal to it ordinary <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVi6yZwpEbGdrcN5Y29ycA" class="cyc_term">radius</a>. Note that, since an axis is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a>, it strictly speaking has infinite length. So when we say that a given axis <code>AXIS</code> of a spheroid <code>SPHEROID</code> has the length <code>DISTANCE</code>, it is really shorthand for saying that the line-segment part of <code>AXIS</code> whose endpoints are where <code>AXIS</code> intersects <code>SPHEROID</code> has length <code>DISTANCE</code>. Equatorial Radius Of Spheroid

Gravitational Force At Point On Earth gravitationalForceAtPointOnEarth <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rOlXgRk-5EdqAAAACs6hO_g" class="cyc_term">gravitationalForceAtPointOnEarth</a> POINT VECTOR)</code> means that <code>VECTOR</code> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjYbpwpEbGdrcN5Y29ycA" class="cyc_term">GravitationalForceVector</a> at <code>POINT</code>, an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvvzxGZwpEbGdrcN5Y29ycA" class="cyc_term">GeographicalPoint_Intangible</a>. See also the corresponding function <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrg19dE2DEdqAAAACs6hO_g" class="cyc_term">GravitationalForceAtPointOnEarthFn</a>.

Clarke1880RGSSpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rI3ivlvlsEdmAAAACs6hO_g" class="cyc_term">Clarke1880RGSSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378249.145) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 293.465 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the Clarke 1880 RGS spheroid

vertical geodetic data A type of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLACWrFFFEdqAAAACs6hO_g" class="cyc_term">VerticalDatum</a>. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLkb-flFFEdqAAAACs6hO_g" class="cyc_term">VerticalGeodeticDatum</a>s are used to determine a location's height relative to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a> VerticalGeodeticDatum

Spheroid spheroid A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPRuk5wpEbGdrcN5Y29ycA" class="cyc_term">TwoDimensionalShapeType</a> and a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv9CgZpwpEbGdrcN5Y29ycA" class="cyc_term">Ellipsoid</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> is an ellipsoid that has two axes (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r4BM6CvVqEdmAAAACs0uFOQ" class="cyc_term">symmetricAxes</a>) of equal length (if all of an ellipsoid's axes are of equal length, it is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgDAn5wpEbGdrcN5Y29ycA" class="cyc_term">Sphere</a>). With respect to a non-spherical spheroid, the axes that are of equal length are equatorial axes, and an axis that is perpendicular to an equatorial axis is a polar axis. (Since a non-spherical spheroid's equatorial axes are coplanar, it therefore has a unique polar axis.) A spheroid whose equatorial axes are longer than its polar axis is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>, and one whose polar axis is longer than its equatorial axes is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a>. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a>. Note that, since an axis is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a>, it strictly speaking has infinite length. So when we say that a given axis <code>AXIS</code> of a spheroid <code>SPHEROID</code> has the length <code>LENGTH</code>, it is really shorthand for saying that the line-segment part of <code>AXIS</code> whose endpoints are where <code>AXIS</code> intersects <code>SPHEROID</code> has <code>LENGTH</code>.

MagneticField A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDGM-MkynEdqAAAACs6hO_g" class="cyc_term">MagneticField</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rCkakrkynEdqAAAACs6hO_g" class="cyc_term">VectorField</a> which assigns a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rudJ3dEylEdqAAAACs6hO_g" class="cyc_term">MagneticForceVector</a> to each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> in some <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvlxdi5wpEbGdrcN5Y29ycA" class="cyc_term">SpaceRegion</a>. magnetic field

ThreeDimensionalCoordinateSystem three-dimensional coordinate system A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rL7uDNv1aEdmAAAACs0uFOQ" class="cyc_term">ThreeDimensionalCoordinateSystem</a> is a frame of reference for specifying the locations of spatial things in a three-dimensional space. Typically, such a system will have three coordinate-value predicates associated with it (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a>). A three-dimensional coordinate system might be a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> or a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> (qq.v.). Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r58-Pov1REdmAAAACs0uFOQ" class="cyc_term">TwoDimensionalCoordinateSystem</a>.

GeographicalLine-Intangible intangible geographical line A specialization of both <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvc-YsJwpEbGdrcN5Y29ycA" class="cyc_term">GeographicalThing_Intangible</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvpeTbpwpEbGdrcN5Y29ycA" class="cyc_term">LineSegment</a> (qq.v.). This is the collection of one-dimensional intangible geographical lines, fixed-location or otherwise. Its specializations include <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwVGrQ5wpEbGdrcN5Y29ycA" class="cyc_term">LatitudeLine</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvWRzmZwpEbGdrcN5Y29ycA" class="cyc_term">LineOfMilitaryForces</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkLfZwpEbGdrcN5Y29ycA" class="cyc_term">GeopoliticalBorder</a>.

EverestSarawakAndSabahSpheroid the Everest Sarawak and Sabah spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rSX0fdPlsEdmAAAACs6hO_g" class="cyc_term">EverestSarawakAndSabahSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377298.556) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 300.8017 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

the OSU 86F spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rfwiRbvlsEdmAAAACs6hO_g" class="cyc_term">OSU86FSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378136.2) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.25722 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). OSU86FSpheroid

datumForCoordinateSystem <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHd0x3lFjEdqAAAACs6hO_g" class="cyc_term">datumForCoordinateSystem</a> DATUM SYSTEM)</code> means that <code>DATUM</code> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4ryo22ZlFEEdqAAAACs6hO_g" class="cyc_term">GeographicDatum</a> upon which an object's coordinates in <code>SYSTEM</code> are referenced. Datum For Coordinate System

force vector ForceVector A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjsEpwpEbGdrcN5Y29ycA" class="cyc_term">VectorInterval</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjHMJwpEbGdrcN5Y29ycA" class="cyc_term">ForceVector</a> is an n-tuple of intervals (where n > 1), one of which is a direction, and one of which expresses a quantity of force. Like the instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAp5wpEbGdrcN5Y29ycA" class="cyc_term">ScalarInterval</a>, the intervals in an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjHMJwpEbGdrcN5Y29ycA" class="cyc_term">ForceVector</a> may be point-valued or cover a range of values. The minimal interval (i.e., point-valued) type of vector interval is exemplified by a vector such as "10 pounds in a horizontal direction". Vectors may also cover a range of values; e.g. "between 10 and 12 Newtons in a vertical direction".

TidalDatum tidal data A type of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLACWrFFFEdqAAAACs6hO_g" class="cyc_term">VerticalDatum</a>. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rXlWJqlFFEdqAAAACs6hO_g" class="cyc_term">TidalDatum</a>s are used to determine a location's height relative to mean sea level. Tidal datums are local datums and should not be extended into areas which have differing hydrographic characteristics without substantiating measurements.

geodesy This is the study of the earth's surface as a whole, in particular the determination of its shape and the relation of its shape to the direction of gravity. Geodesy

UTMCoordinateSystem A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> that sections the earth into many longitude and latitude zones. See <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv00kUpwpEbGdrcN5Y29ycA" class="cyc_term">utmLongitudeZone</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rFQ9LurUwEdqAAAACs6hO_g" class="cyc_term">utmLatitudeZone</a>. The cartesian coordinates of points within a single UTM zone are expressed using the predicates <code><a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwATnrpwpEbGdrcN5Y29ycA" class="cyc_term">easting</a></code> and <code><a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvnMVVZwpEbGdrcN5Y29ycA" class="cyc_term">northing</a></code>. the UTM coordinate system

A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rudJ3dEylEdqAAAACs6hO_g" class="cyc_term">MagneticForceVector</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjHMJwpEbGdrcN5Y29ycA" class="cyc_term">ForceVector</a> that measures the magnitude and direction of the magnetic force exerted on a body at a given point. MagneticForceVector magnetic force vector

A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a> is a "squashed" spheroid: one whose polar radius is less than its equatorial radius (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a>). Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a>. OblateSpheroid oblate spheroid

Newtonian gravity PhysicalForce-NewtonianGravity

the Clarke 1880 SGA spheroid Clarke1880SGASpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rN5lT_vlsEdmAAAACs6hO_g" class="cyc_term">Clarke1880SGASpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378249.2) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 293.46598 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

This predicate relates a spatial reference system (instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a>) with its Well Known Text representation (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rjNh0ZuQjEdmAAAACs6hO_g" class="cyc_term">WellKnownTextString</a>). Well Known Text String For Coordinate System wellKnownTextStringForCoordinateSystem

the Bessel Namibia spheroid BesselNamibiaSpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r-hkwOvlrEdmAAAACs6hO_g" class="cyc_term">BesselNamibiaSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377483.865) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 299.1528128 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

Plessis1817Spheroid the Plessis 1817 spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4ri4HP0vlsEdmAAAACs6hO_g" class="cyc_term">Plessis1817Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6376523) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 308.64 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

NAD27CoordinateSystem The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> based on the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r7CzGulFHEdqAAAACs6hO_g" class="cyc_term">NorthAmericanDatum1927</a> datum. NAD 27 Coordinate system

the ocean EarthsOceanSea The interconnected expanse of sea water that encircles the continents and makes up 71% of the Earth's surface area.

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rhlQBsPlsEdmAAAACs6hO_g" class="cyc_term">OSU91ASpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378136.3) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.25722 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the OSU91A spheroid OSU91ASpheroid

VerticalDatum vertical data A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLACWrFFFEdqAAAACs6hO_g" class="cyc_term">VerticalDatum</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4ryo22ZlFEEdqAAAACs6hO_g" class="cyc_term">GeographicDatum</a> which is used to accruately determine the height of a geographical location above (or below) some reference surface. For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLkb-flFFEdqAAAACs6hO_g" class="cyc_term">VerticalGeodeticDatum</a>s are used to determine a location's height relative to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a>, while <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rXlWJqlFFEdqAAAACs6hO_g" class="cyc_term">TidalDatum</a>s are used to determine a location's height relative to mean sea level.

the Clarke 1880 Benoit spheroid Clarke1880BenoitSpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rFNFi0PlsEdmAAAACs6hO_g" class="cyc_term">Clarke1880BenoitSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378300.79) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 293.466234571 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

primeMeridianForCoordinateSystem Prime Meridian For Coordinate System <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rIRrhPlFjEdqAAAACs6hO_g" class="cyc_term">primeMeridianForCoordinateSystem</a> MERIDIAN SYSTEM)</code> means that <code>MERIDIAN</code> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvdq0oZwpEbGdrcN5Y29ycA" class="cyc_term">LongitudeLine</a> from which the azimuth angle for <code>SYSTEM</code> (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a>) measures angles. That is, if <code>AZIMUTH-PRED</code> is the azimuth angle predicate for <code>SYSTEM</code>, then <code>(AZIMUTH-PRED MERIDIAN (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirWpwpEbGdrcN5Y29ycA" class="cyc_term">Degree_UnitOfAngularMeasure</a> 0))</code> and the value of <code>AZIMUTH-PRED</code> is positive for locations to the east of <code>MERIDIAN</code> and negative for locations west of <code>MERIDIAN</code>. Often, <code>MERIDIAN</code> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwRFVJJwpEbGdrcN5Y29ycA" class="cyc_term">PrimeMeridian_Greenwich</a>, however there are some coordinate systems that use other meridians.

ScalarField scalar field A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rC1VvTEynEdqAAAACs6hO_g" class="cyc_term">ScalarField</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjuppwpEbGdrcN5Y29ycA" class="cyc_term">Field_Mathematical</a> which assigns a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAp5wpEbGdrcN5Y29ycA" class="cyc_term">ScalarInterval</a> to each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> in some <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvlxdi5wpEbGdrcN5Y29ycA" class="cyc_term">SpaceRegion</a>.

WGS84 WGS84CoordinateSystem The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> based on the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r1zTX2lFkEdqAAAACs6hO_g" class="cyc_term">WorldGeodeticSurvey1984</a> datum.

geodetic control network GeodeticControlNetwork A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYwcdYFFFEdqAAAACs6hO_g" class="cyc_term">GeodeticControlNetwork</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv1YoXZwpEbGdrcN5Y29ycA" class="cyc_term">Network</a> of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYFjYplFFEdqAAAACs6hO_g" class="cyc_term">GeodeticControlPoint</a>s which is used to establish an accurate #$Datum for determining the position of locations on some portion of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a>.

spheroidTypeForDatum <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rZgRXqFFFEdqAAAACs6hO_g" class="cyc_term">spheroidTypeForDatum</a> SPHEROID-TYPE DATUM)</code> means that some instance of <code>SPHEROID-TYPE</code> is used to locally approximate a patch of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a> near the benchmark point for <code>DATUM</code>. Spheroid Type For Datum

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHEjTkPlsEdmAAAACs6hO_g" class="cyc_term">Clarke1880IGNSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378249.2) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 293.46602 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). Clarke1880IGNSpheroid the Clarke 1880 IGN spheroid

North American Datum 1927 The North American Datum 1927. This datum was established by the United States National Ocean Service (NOS), later known as National Oceanographic and Atmospheric Agency (NOAA). From 1927 to 1987 all U.S. government charts of the contiguous United States were based on the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r7CzGulFHEdqAAAACs6hO_g" class="cyc_term">NorthAmericanDatum1927</a>. After 1989, the U.S. officially switched to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rImU26lFIEdqAAAACs6hO_g" class="cyc_term">NorthAmericanDatum1983</a>. NorthAmericanDatum1927

GravitationalField A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDq2dDkynEdqAAAACs6hO_g" class="cyc_term">GravitationalField</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rCkakrkynEdqAAAACs6hO_g" class="cyc_term">VectorField</a> which assigns a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjYbpwpEbGdrcN5Y29ycA" class="cyc_term">GravitationalForceVector</a> to each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> in some <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvlxdi5wpEbGdrcN5Y29ycA" class="cyc_term">SpaceRegion</a>. gravitational field

the Airy spheroid AirySpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r31N4lvlrEdmAAAACs6hO_g" class="cyc_term">AirySpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377563.396) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 299.3249646 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

North American Datum 1983 The North American Datum 1983. This datum was established by the National Oceanographic and Atmospheric Agency in 1983 and has been the official datum for all U.S. government charts of the contiguous United States since 1989. It is a refinement of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r7CzGulFHEdqAAAACs6hO_g" class="cyc_term">NorthAmericanDatum1927</a>. NorthAmericanDatum1983

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rVFUmYvlsEdmAAAACs6hO_g" class="cyc_term">GRS1980Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378137) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.257222101 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the GRS 1980 spheroid GRS1980Spheroid

meter An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViKt5wpEbGdrcN5Y29ycA" class="cyc_term">UnitOfDistance</a>. When applied to a number or pair of numbers, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> returns an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a> as its value. For example, (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 5) is a distance of five meters. Meter

the Clarke 1866 spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_2qznPlrEdmAAAACs6hO_g" class="cyc_term">Clarke1866Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378206.4) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 294.9786982 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). Clarke1866Spheroid

sridForCoordinateSystem (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNUyHAv-DEdmAAAACs6hO_g" class="cyc_term">sridForCoordinateSystem</a> SRID SYSTEM) means the SYSTEM is the spatial reference system (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a>) which is identified by SRID in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rN1IekteGEdmAAAAH6Q2cKw" class="cyc_term">OpenGISSimpleFeaturesSpecificationForSQL</a>. See also the corresponding function <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNAs3CP-DEdmAAAACs6hO_g" class="cyc_term">CoordinateSystemFromSRIDFn</a>. Srid For Coordinate System

electric force vector ElectricForceVector An <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rfrB0OEymEdqAAAACs6hO_g" class="cyc_term">ElectricForceVector</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjHMJwpEbGdrcN5Y29ycA" class="cyc_term">ForceVector</a> that measures the magnitude and direction of the electric force exerted on a body at a given point.

A binary predicate that relates a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViBpJwpEbGdrcN5Y29ycA" class="cyc_term">FunctionalSlot</a> predicate to a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a> (qq.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> PRED SYS)</code> means that <code>PRED</code> is one of the binary predicates used to describe the location of spatial things in the coordinate system <code>SYS</code>. The first argument of <code>PRED</code> will be restricted (via <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViBGJwpEbGdrcN5Y29ycA" class="cyc_term">arg1Isa</a>) to instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a> or some specialization thereof. In geometry, typically only points have specific coordinate values; the location of a spatially extended object is given by an equation that is satisfied by (all and only) the points spatially subsumed by the object. But here we allow for spatially extended objects to have coordinate values attributed to them directly. So in an assertion of the form <code>(PRED THING VALUE)</code>, the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a> <code>THING</code> need not be an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a>. In certain contexts we might stipulate, for example, that such an assertion is true if and only if <code>THING</code> subsumes a point <code>POINT</code> such that <code>(PRED POINT VALUE)</code> holds. There are various specializations of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> currently reified in the Cyc knowledge base, each of which is applicable to one or the other of the two main types of coordinate systems. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuxEKJwpEbGdrcN5Y29ycA" class="cyc_term">xAxisPredicateOfSystem</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvudnoZwpEbGdrcN5Y29ycA" class="cyc_term">yAxisPredicateOfSystem</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPpz75wpEbGdrcN5Y29ycA" class="cyc_term">zAxisPredicateOfSystem</a> all apply to <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a>s. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvr7jXZwpEbGdrcN5Y29ycA" class="cyc_term">radialDistancePredicate</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a> all apply to <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a>s. Coordinate Value Predicate Of System coordinateValuePredicateOfSystem

A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvaEcosFuQdiNopS8VV8ODg" class="cyc_term">MeasurableQuantitySlot</a> (q.v.) that is used to specify (partially) the size a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a>. <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rpBDjnvlsEdmAAAACs0uFOQ" class="cyc_term">spheroidSemiminorAxisLength</a> SPHEROID DISTANCE)</code> means that <code>DISTANCE</code> is one-half of the length of <code>SPHERIOID</code>'s minor axis. The minor axis of a spheroid is by definition the shortest of its three principle axes. For an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a> (q.v.), the semi-minor axis length is equal to its polar radius (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a>). For a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a> (q.v.), the semi-minor axis length is equal to its equatorial radius (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a>). Together, the semi-minor axis length and the semi-major axis length (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) of a spheroid determine its flattening and inverse flattening (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). For example, if the semi-major and semi-minor axis lengths are <code>MAJ</code> and <code>MIN</code>, respectively, then the inverse flattening is <code>INVFLAT = MAJ/(MAJ-MIN)</code>. Note that, since an axis is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a>, it strictly speaking has infinite length. So when we say that a given axis <code>AXIS</code> of a spheroid <code>SPHEROID</code> has the length <code>LENGTH</code>, it is really shorthand for saying that the line-segment part of <code>AXIS</code> whose endpoints are where <code>AXIS</code> intersects <code>SPHEROID</code> has <code>LENGTH</code>. Spheroid Semiminor Axis Length spheroidSemiminorAxisLength

the Struve 1860 spheroid Struve1860Spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rkp51rvlsEdmAAAACs6hO_g" class="cyc_term">Struve1860Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378297) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 294.73 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

magneticDeclinationAtPointOnEarth Magnetic Declination At Point On Earth The magnetic declination at any geographical point, <code>POINT</code>, on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> is the angle between the vector positioned at <code>POINT</code> and pointing at the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzRiJwpEbGdrcN5Y29ycA" class="cyc_term">AxialNorthPoleOfEarth</a> and the horizontal component of the Earth's magnetic field at <code>POINT</code>, measured clockwise from the axial North pole. In <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViqDZwpEbGdrcN5Y29ycA" class="cyc_term">CycL</a>, this relation is denoted by <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r9lISeE-1EdqAAAACs6hO_g" class="cyc_term">magneticDeclinationAtPointOnEarth</a> POINT DECLINATION)</code>.

A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r6ZFcIFFEEdqAAAACs6hO_g" class="cyc_term">HorizontalDatum</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4ryo22ZlFEEdqAAAACs6hO_g" class="cyc_term">GeographicDatum</a> which is used to accurately determine the horziontal position of a geographic location. horizontal data HorizontalDatum

A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjUoJwpEbGdrcN5Y29ycA" class="cyc_term">FrameOfReference</a> (q.v.). This is the collection of systems with respect to which the locations of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a>s can be specified. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a> has an associated suite of coordinate value predicates (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> and its specializations), which assign coordinates to spatial things. The two most common types of coordinate systems are <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a>s and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a>s (qq.v.). The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a> is an example of the latter; it has two coordinate value predicates, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjw3ZwpEbGdrcN5Y29ycA" class="cyc_term">latitude</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjwmpwpEbGdrcN5Y29ycA" class="cyc_term">longitude</a>, both of which assign <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVir1pwpEbGdrcN5Y29ycA" class="cyc_term">AngularDistance</a>s to spatial things. CoordinateSystem coordinate system

GeographicDatum geographic data A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4ryo22ZlFEEdqAAAACs6hO_g" class="cyc_term">GeographicDatum</a> is defined as any numerical or geometrical quantity, or set of quantities, which serves as a reference point from which to accurately measure geographic position.

isogonic line IsogonicLine An <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rmhpNoE--EdqAAAACs6hO_g" class="cyc_term">IsogonicLine</a> is an intangible curve on the Earth's surface (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwCl_n5wpEbGdrcN5Y29ycA" class="cyc_term">EarthsTopographicSurface</a>) connecting points of constant magnetic declination.

geomatics This is a field which applies computerized cartography, spatial analysis, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvnC9xpwpEbGdrcN5Y29ycA" class="cyc_term">GeographicInformationSystem</a>s to cartography in the broadest sense. Geomatics

ElectricField electric field An <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDZeTIEynEdqAAAACs6hO_g" class="cyc_term">ElectricField</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rCkakrkynEdqAAAACs6hO_g" class="cyc_term">VectorField</a> which assigns an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rfrB0OEymEdqAAAACs6hO_g" class="cyc_term">ElectricForceVector</a> to each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> in some <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvlxdi5wpEbGdrcN5Y29ycA" class="cyc_term">SpaceRegion</a>.

WarOfficeSpheroid the War Office spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rmeN2evlsEdmAAAACs6hO_g" class="cyc_term">WarOfficeSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378300.583) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 296 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

the Australian national spheroid AustralianSpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r5mdopPlrEdmAAAACs6hO_g" class="cyc_term">AustralianSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378160) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.25 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

xAxisPredicateOfSystem X Axis Predicate Of System A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> that relates a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvaEcosFuQdiNopS8VV8ODg" class="cyc_term">MeasurableQuantitySlot</a> predicate to a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> (qq.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuxEKJwpEbGdrcN5Y29ycA" class="cyc_term">xAxisPredicateOfSystem</a> X-PRED SYS)</code> means that <code>X-PRED</code> is the binary predicate used to state x-coordinate values in the Cartesian coordinate system <code>SYS</code>, i.e. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a>s from the y-axis (if <code>SYS</code> is 2-D) or from the yz-plane (if <code>SYS</code> is 3-D). Thus, for example, <code>(X-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 5))</code> would mean that, in <code>SYS</code>, the x-coordinate value of <code>POINT</code> is 5 meters. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvudnoZwpEbGdrcN5Y29ycA" class="cyc_term">yAxisPredicateOfSystem</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPpz75wpEbGdrcN5Y29ycA" class="cyc_term">zAxisPredicateOfSystem</a>.

<code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rPH1RxE-5EdqAAAACs6hO_g" class="cyc_term">magneticForceAtPointOnEarth</a> POINT VECTOR)</code> means that <code>VECTOR</code> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rudJ3dEylEdqAAAACs6hO_g" class="cyc_term">MagneticForceVector</a> at <code>POINT</code>, an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvvzxGZwpEbGdrcN5Y29ycA" class="cyc_term">GeographicalPoint_Intangible</a>. See also the corresponding function <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rTWbQIEyrEdqAAAACs6hO_g" class="cyc_term">MagneticForceAtPointOnEarthFn</a>. magneticForceAtPointOnEarth Magnetic Force At Point On Earth

Earth's ground An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjQsJwpEbGdrcN5Y29ycA" class="cyc_term">Ground</a> (q.v.). <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjBN5wpEbGdrcN5Y29ycA" class="cyc_term">EarthsGround</a> denotes the surface of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> that is not relatively permanently under a body of water. Parts of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjBN5wpEbGdrcN5Y29ycA" class="cyc_term">EarthsGround</a> include the tops of glaciers, the unsubmerged parts of deserts, beaches, prairies, etc. EarthsGround

altitudeAnglePredicate Altitude Angle Predicate A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> (q.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a> ALT-PRED SYS)</code> means that <code>ALT-PRED</code> is the binary predicate used to express colatitude or polar angle coordinates of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a>s in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> (q.v.) <code>SYS</code>. <code>ALT-PRED</code>'s two argument-places will be restricted (via <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuItPZwpEbGdrcN5Y29ycA" class="cyc_term">argIsa</a>) to instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a> (or some specialization thereof) and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVir1pwpEbGdrcN5Y29ycA" class="cyc_term">AngularDistance</a>, respectively. Thus (e.g.), <code>(ALT-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirWpwpEbGdrcN5Y29ycA" class="cyc_term">Degree_UnitOfAngularMeasure</a> 30))</code> would mean that, in <code>SYS</code>, <code>POINT</code> is on a ray that terminates at the pole and makes a 30-degree angle with the z-axis. For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjw3ZwpEbGdrcN5Y29ycA" class="cyc_term">latitude</a> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a> for the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a>. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvr7jXZwpEbGdrcN5Y29ycA" class="cyc_term">radialDistancePredicate</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a>.

ProlateSpheroid A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a> is a "pointy" spheroid: one whose polar radius is greater than its equatorial radius (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a>). Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>. prolate spheroid

azimuthAnglePredicate A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> (q.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a> AZI-PRED SYS)</code> means that <code>AZIPRED</code> is the binary predicate used to express azimuth angle coordinates of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a>s in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> (q.v.) <code>SYS</code>. <code>PRED</code>'s two argument-places will be restricted (via <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuItPZwpEbGdrcN5Y29ycA" class="cyc_term">argIsa</a>) to instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a> (or some specialization thereof) and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVir1pwpEbGdrcN5Y29ycA" class="cyc_term">AngularDistance</a>, respectively. Thus (e.g.), <code>(AZI-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirWpwpEbGdrcN5Y29ycA" class="cyc_term">Degree_UnitOfAngularMeasure</a> 30))</code> would mean that, in <code>SYS</code>, <code>POINT</code> (or, in a 3-D system, <code>POINT</code>'s image on the xy plane) is on a ray that terminates at the pole and makes a 30-degree angle (counter-clockwise) with the polar axis. For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjwmpwpEbGdrcN5Y29ycA" class="cyc_term">longitude</a> is the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a> for the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a>. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvr7jXZwpEbGdrcN5Y29ycA" class="cyc_term">radialDistancePredicate</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a>. Azimuth Angle Predicate

An <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rm8K5lE--EdqAAAACs6hO_g" class="cyc_term">AgonicLine</a> is an intangible curve on the Earth's surface (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwCl_n5wpEbGdrcN5Y29ycA" class="cyc_term">EarthsTopographicSurface</a>) connecting points of 0 degrees magnetic declination. AgonicLine agonic line

Spheroid Inverse Flattening A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNW5wpEbGdrcN5Y29ycA" class="cyc_term">ScalarIntervalSlot</a> (q.v.) that is used to specify the shape of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> in terms of a real number (or numeric interval). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a> SPHEROID INVFLAT)</code> means that <code>SPHEROID</code> has the inverse flattening <code>INVFLAT</code>. Where <code>SPHEROID</code>'s semi-major axis length (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) is <code>MAJ</code> and its semi-minor axis length (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rpBDjnvlsEdmAAAACs0uFOQ" class="cyc_term">spheroidSemiminorAxisLength</a>), <pre> INVFLAT = MAJ/(MAJ-MIN) . </pre> An important use of the predicate <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a> is in representing certain geospatial reference systems. If it is known whether a given spheroid is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a> or a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a> (qq.v.), its inverse flattening and semi-major axis length determine its precise shape and size. spheroidInverseFlattening

the Clarke 1866 Michigan spheroid Clarke1866MichiganSpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rBkWDIvlsEdmAAAACs6hO_g" class="cyc_term">Clarke1866MichiganSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378693.704) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 294.978684677 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

polar coordinate system PolarCoordinateSystem A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> consists of a of a fixed <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> called the origin or pole, and a fixed <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh19N5wpEbGdrcN5Y29ycA" class="cyc_term">Ray_Geometrical</a> that terminates at the pole, called the polar axis, which is usually taken to be the positive half of the x-axis. A fixed <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a> passing through the pole and perpendicular to the x-axis is taken to be the y-axis. For three-dimensional systems, the straight line passing through the pole and perpendicular to both the x and y axes is the z-axis. In a two-dimensional polar coordinate system (also called a circular coordinate system), the location of a given point P in the plane is specified by giving (i) the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a> from the pole to P (called the radius) and (ii) the size of the angle (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVir1pwpEbGdrcN5Y29ycA" class="cyc_term">AngularDistance</a>) that the ray from the pole through P makes with the polar axis. Two common types of three-dimensional polar coordinate systems are cylindrical coordinate systems and spherical coordinate systems. In a cylindrical system, the location of a point P is specified by giving (i') the distance (or radius) between the z-axis and P, (ii') the angular distance (called the azimuth or longitude) between the polar axis and the line from the origin to the projection of P onto the xy-plane, and (iii') the signed distance (or height) from the xy-plane to P. In a spherical system, the location of a point P is specified by giving (i'') the radius [defined as in (i) above], (ii'') the azimuth or longitude [defined as in (ii') above], and (iii'') the angular distance (called the colatitude or polar angle) between the z-axis and the line from the origin to P. The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a> (q.v.) is an example of a spherical coordinate system. Given a particular polar coordinate system, predicates for specifying the radius, the azimuth, and the colatitude of a point can be defined using the meta-predicates <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvr7jXZwpEbGdrcN5Y29ycA" class="cyc_term">radialDistancePredicate</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a>, respectively. Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a>.

radialDistancePredicate A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> (q.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvr7jXZwpEbGdrcN5Y29ycA" class="cyc_term">radialDistancePredicate</a> RAD-PRED SYS)</code> means that <code>RAD-PRED</code> is the binary predicate used to express the radial distance coordinates of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a>s in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> (q.v.) <code>SYS</code>. <code>RAD-PRED</code>'s two argument-places will be restricted (via <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuItPZwpEbGdrcN5Y29ycA" class="cyc_term">argIsa</a>) to instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjpUZwpEbGdrcN5Y29ycA" class="cyc_term">SpatialThing</a> (or some specialization thereof) and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a>, respectively. Thus, for example <code>(RAD-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 5))</code> would mean that, in <code>SYS</code>, the distance from <code>POINT</code> to the pole is 5 meters. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a>. Radial Distance Predicate

KrasovskySpheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rdKniSvlsEdmAAAACs6hO_g" class="cyc_term">KrasovskySpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378245) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.3 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the Krasovsky spheroid

MagneticPoleOfPlanet A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv9DJs5wpEbGdrcN5Y29ycA" class="cyc_term">GeographicalThing_Intangible_MovableLocation</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rOGaXOEy0EdqAAAACs6hO_g" class="cyc_term">MagneticPoleOfPlanet</a> is a point on the surface of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRL5wpEbGdrcN5Y29ycA" class="cyc_term">Planet</a> where the lines of force of its magnetic field are vertical. Two notable instances of this collection are <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rObqWcEy0EdqAAAACs6hO_g" class="cyc_term">MagneticNorthPoleOfEarth</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlE04Xky0EdqAAAACs6hO_g" class="cyc_term">MagneticSouthPoleOfEarth</a>. magnetic pole

A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYFjYplFFEdqAAAACs6hO_g" class="cyc_term">GeodeticControlPoint</a> is a stationary point on the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> whose horzontal and/or vertical position with respect to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a> has been accruately determined. geodetic control point GeodeticControlPoint

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDXzULvlsEdmAAAACs6hO_g" class="cyc_term">Clarke1880ArcSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378249.145) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 293.466307656 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). Clarke1880ArcSpheroid the Clarke 1880 arc spheroid

A predicate which relates a field (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjuppwpEbGdrcN5Y29ycA" class="cyc_term">Field_Mathematical</a>) with the region of space (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvlxdi5wpEbGdrcN5Y29ycA" class="cyc_term">SpaceRegion</a>) in which the field is defined. <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rG-gnekyqEdqAAAACs6hO_g" class="cyc_term">fieldInRegion</a> FIELD REGION)</code> means that for each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a>, <code>POINT</code> that is incident in <code>REGION</code> (see #$incidentInSpaceRegion), the quantity <code>(FIELD POINT)</code> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r9WcgvD_6EdqAAAACs0uFOQ" class="cyc_term">defined</a>. fieldInRegion Field In Region

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rTvBK-PlsEdmAAAACs6hO_g" class="cyc_term">ModifiedEverest1948Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377304.063) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 300.8017 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the modified Everest 1948 spheroid ModifiedEverest1948Spheroid

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r4TREuvlrEdmAAAACs6hO_g" class="cyc_term">ModifiedAirySpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 677340.189) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 299.3249646 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the modified Airy spheroid ModifiedAirySpheroid

The shape of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a>'s gravitational equipotential surface. That is, the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a> is the unique surface which satisfies the following conditions: 1. Given any <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a>, <code>POINT</code>, on the surface, the normal line at <code>POINT</code> (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r2Wf6eDXpEdqAAAACs6hO_g" class="cyc_term">normalLineAtPointOnSurface</a>) is parallel to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjYbpwpEbGdrcN5Y29ycA" class="cyc_term">GravitationalForceVector</a> at <code>POINT</code>; 2. The magnitude of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjYbpwpEbGdrcN5Y29ycA" class="cyc_term">GravitationalForceVector</a> at <code>POINT</code> is constant for all <code>POINT</code>s on the surface. A consequence of this definition is that the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rrLnJIE-7EdqAAAACs6hO_g" class="cyc_term">EarthsGeoidSurface</a> is the surface to which the oceans would conform over the entire planet, if they were free to adjust to the combined effect of the Earth's mass attraction and the centrifugal force of the Earth's rotation. Earths Geoid Surface EarthsGeoidSurface

ModifiedBesselSpheroid the modified Bessel spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r9QHgQvlrEdmAAAACs6hO_g" class="cyc_term">ModifiedBesselSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377492.018) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 299.1528128 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>).

geodetic coordinate system GeodeticCoordinateSystem A polar coordinate system centered on the center of the earth, and in terms of which locations of things can be expressed using the two predicates <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjw3ZwpEbGdrcN5Y29ycA" class="cyc_term">latitude</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjwmpwpEbGdrcN5Y29ycA" class="cyc_term">longitude</a> (respectively, the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvmmn9ZwpEbGdrcN5Y29ycA" class="cyc_term">altitudeAnglePredicate</a> and the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNP525wpEbGdrcN5Y29ycA" class="cyc_term">azimuthAnglePredicate</a> of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a>). The latitude of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzQjJwpEbGdrcN5Y29ycA" class="cyc_term">EarthsEquator</a> is 0 degrees; the latitude of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzRiJwpEbGdrcN5Y29ycA" class="cyc_term">AxialNorthPoleOfEarth</a> is 90 degrees; and the longitude of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwRFVJJwpEbGdrcN5Y29ycA" class="cyc_term">PrimeMeridian_Greenwich</a> is 0 degrees. (These assertions 'pin down' the orientation of the earth with respect to the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVWMJwpEbGdrcN5Y29ycA" class="cyc_term">GeodeticCoordinateSystem</a>.) See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjw3ZwpEbGdrcN5Y29ycA" class="cyc_term">latitude</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjwmpwpEbGdrcN5Y29ycA" class="cyc_term">longitude</a>.

the WGS 1984 spheroid The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4roRYHqvlsEdmAAAACs6hO_g" class="cyc_term">WGS1984Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378137) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.257223563 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). WGS1984Spheroid

Magnetic Inclination At Point On Earth magneticInclinationAtPointOnEarth The magnetic inclination at any geographical point, <code>POINT</code>, on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> is the angle between the gravitational vector at <code>POINT</code> and the vertical component of the Earth's magnetic field at <code>POINT</code>. In <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViqDZwpEbGdrcN5Y29ycA" class="cyc_term">CycL</a>, this relation is denoted by <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r9KYxrE-1EdqAAAACs6hO_g" class="cyc_term">magneticInclinationAtPointOnEarth</a> POINT INCLINATION)</code>. The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rObqWcEy0EdqAAAACs6hO_g" class="cyc_term">MagneticNorthPoleOfEarth</a> is by definition the point on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> where the inclination is (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirWpwpEbGdrcN5Y29ycA" class="cyc_term">Degree_UnitOfAngularMeasure</a> 0), and the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlE04Xky0EdqAAAACs6hO_g" class="cyc_term">MagneticSouthPoleOfEarth</a> is the point on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> where the inclination is (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirWpwpEbGdrcN5Y29ycA" class="cyc_term">Degree_UnitOfAngularMeasure</a> 180).

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4redpNfPlsEdmAAAACs6hO_g" class="cyc_term">NWL9DSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378145) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 298.25 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). NWL9DSpheroid the NWL 9D spheroid

World Geodetic Survey 1984 WorldGeodeticSurvey1984 The datum established by the World Geodetic Survey of 1984. The WGS system is not based on a single <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYFjYplFFEdqAAAACs6hO_g" class="cyc_term">GeodeticControlPoint</a>, but on many points, fixed with extreme precision by the Global Positioning Satellite system. It is applicable worldwide and has been widely adopted around the world as the base reference datum.

zAxisPredicateOfSystem A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> that relates a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvaEcosFuQdiNopS8VV8ODg" class="cyc_term">MeasurableQuantitySlot</a> predicate to a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> (qq.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPpz75wpEbGdrcN5Y29ycA" class="cyc_term">zAxisPredicateOfSystem</a> Z-PRED SYS)</code> means that <code>Z-PRED</code> is the binary predicate used to state z-coordinate values in the 3-D Cartesian coordinate system <code>SYS</code>, i.e. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a>s from the xy-plane. Thus, for example, <code>(Z-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 5))</code> would mean that, in <code>SYS</code>, the z-coordinate value of <code>POINT</code> is 5 meters. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuxEKJwpEbGdrcN5Y29ycA" class="cyc_term">xAxisPredicateOfSystem</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvudnoZwpEbGdrcN5Y29ycA" class="cyc_term">yAxisPredicateOfSystem</a>. Z Axis Predicate Of System

two-dimensional coordinate system TwoDimensionalCoordinateSystem A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a> (q.v.). Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r58-Pov1REdmAAAACs0uFOQ" class="cyc_term">TwoDimensionalCoordinateSystem</a> is a frame of reference for specifying the locations of spatial things with respect to a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rN1T3Nlv9QdeJ7LFO9u6POw" class="cyc_term">Plane</a>. Typically, such a system will have just two coordinate-value predicates associated with it (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a>). A two-dimensional coordinate system might be a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> or a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a> (qq.v.). Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rL7uDNv1aEdmAAAACs0uFOQ" class="cyc_term">ThreeDimensionalCoordinateSystem</a>.

A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv21MfpwpEbGdrcN5Y29ycA" class="cyc_term">CoordinateSystem</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> is based on two or three perpendicular axes (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a>) that intersect at a point, called the origin. Two axes are used for coordinating a two-dimensional space; three axes are used for coordinating a three-dimensional space. Any point in the space coordinated by the system can be specified by a pair (or triple) of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a>s, representing distances from the origin along each of the two (or three) axes. More precisely, the axes of a given Cartesian coordinate system are respectively designated its x-axis, its y-axis, and (if it has one) its z-axis. The x-coordinate of a given <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwKUKtJwpEbGdrcN5Y29ycA" class="cyc_term">Point</a> measures its least distance from the y-axis (in a 2D system) or from the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rN1T3Nlv9QdeJ7LFO9u6POw" class="cyc_term">Plane</a> defined by the y and z axes (in a 3D system). And similarly for the y-coordinate and (if it has one) the z-coordinate of the point. Given a particular Cartesian coordinate system, binary predicates for giving a point's x-, y-, and z-coordinates can be defined using the meta-predicates <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuxEKJwpEbGdrcN5Y29ycA" class="cyc_term">xAxisPredicateOfSystem</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvudnoZwpEbGdrcN5Y29ycA" class="cyc_term">yAxisPredicateOfSystem</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPpz75wpEbGdrcN5Y29ycA" class="cyc_term">zAxisPredicateOfSystem</a>, respectively. Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv0y055wpEbGdrcN5Y29ycA" class="cyc_term">PolarCoordinateSystem</a>. CartesianCoordinateSystem Cartesian coordinate system

A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwOSbUJwpEbGdrcN5Y29ycA" class="cyc_term">sizeParameterOfObject</a>. <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_8mo2PlOEdmAAAACs0uFOQ" class="cyc_term">polarRadiusOfSpheroid</a> SPHEROID DISTANCE)</code> means that <code>DISTANCE</code> is one-half the length of <code>SPHEROID</code>'s polar axis. Whenever two <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r4BM6CvVqEdmAAAACs0uFOQ" class="cyc_term">symmetricAxes</a> (q.v.) of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzCm-HubNQdaO7ZipW2UPxw" class="cyc_term">Spheroid</a> that is not a perfect <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgDAn5wpEbGdrcN5Y29ycA" class="cyc_term">Sphere</a> have the same length, they are both equatorial axes of the spheroid (cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbuaGTPlJEdmAAAACs0uFOQ" class="cyc_term">equatorialRadiusOfSpheroid</a>). All of the equatorial axes of such a spheroid lie in a single plane; and the (unique) symmetric-axis of the spheroid that is perpendicular with its equatorial axes is known as its polar axis. If a spheroid's equatorial radius is greater than its polar radius, it is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>; if its polar radius is greater than its equatorial radius, it is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHAo0yveyEdmAAAACs0uFOQ" class="cyc_term">ProlateSpheroid</a>. The greater radius (whichever it might be) measures the spheroid's semi-major axis (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>). A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgDAn5wpEbGdrcN5Y29ycA" class="cyc_term">Sphere</a>'s polar and equatorial radii are both equal to its ordinary <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVi6yZwpEbGdrcN5Y29ycA" class="cyc_term">radius</a>. Note that, since an axis is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjC4JwpEbGdrcN5Y29ycA" class="cyc_term">Line_Straight</a>, it strictly speaking has infinite length. So when we say that a given axis <code>AXIS</code> of a spheroid <code>SPHEROID</code> has the length <code>DISTANCE</code>, it is really shorthand for saying that the line-segment part of <code>AXIS</code> whose endpoints are where <code>AXIS</code> intersects <code>SPHEROID</code> has length <code>DISTANCE</code>. polarRadiusOfSpheroid Polar Radius Of Spheroid

One of two instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rOGaXOEy0EdqAAAACs6hO_g" class="cyc_term">MagneticPoleOfPlanet</a> found on <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a>. The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlE04Xky0EdqAAAACs6hO_g" class="cyc_term">MagneticSouthPoleOfEarth</a> is the point where the Earth's magnetic field (see #$MagneticFieldOfPlanetEarthFn) points directly up (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViJqZwpEbGdrcN5Y29ycA" class="cyc_term">Up_Directly</a>). Due to the dynamics of the field, the pole is not stationary. MagneticSouthPoleOfEarth the Magnetic South Pole

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r7g_H6vlrEdmAAAACs6hO_g" class="cyc_term">BesselSpheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6377397.155) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 299.1528128 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the Bessel spheroid BesselSpheroid

The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rbb7YZPlsEdmAAAACs6hO_g" class="cyc_term">International1924Spheroid</a> is the collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rQVBN3ve_EdmAAAACs0uFOQ" class="cyc_term">OblateSpheroid</a>s with a semi-major axis of length (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 6378388) (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rT-8egPVMEdmAAAACs0uFOQ" class="cyc_term">spheroidSemimajorAxisLength</a>) and an inverse flattening of 297.0 (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rU3cTwvV_EdmAAAACs0uFOQ" class="cyc_term">spheroidInverseFlattening</a>). the International 1924 spheroid International1924Spheroid

Y Axis Predicate Of System A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rve1AOZwpEbGdrcN5Y29ycA" class="cyc_term">coordinateValuePredicateOfSystem</a> that relates a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvaEcosFuQdiNopS8VV8ODg" class="cyc_term">MeasurableQuantitySlot</a> predicate to a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIU_XZwpEbGdrcN5Y29ycA" class="cyc_term">CartesianCoordinateSystem</a> (qq.v.). <code>(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvudnoZwpEbGdrcN5Y29ycA" class="cyc_term">yAxisPredicateOfSystem</a> Y-PRED SYS)</code> means that <code>Y-PRED</code> is the binary predicate used to state y-coordinate values in the Cartesian coordinate system <code>SYS</code>, i.e. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAmpwpEbGdrcN5Y29ycA" class="cyc_term">Distance</a>s from the x-axis (if <code>SYS</code> is 2-D) or from the xz-plane (if <code>SYS</code> is 3-D). Thus, for example, <code>(Y-PRED POINT (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjRp5wpEbGdrcN5Y29ycA" class="cyc_term">Meter</a> 5))</code> would mean that, in <code>SYS</code>, the y-coordinate value of <code>POINT</code> is 5 meters. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvuxEKJwpEbGdrcN5Y29ycA" class="cyc_term">xAxisPredicateOfSystem</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPpz75wpEbGdrcN5Y29ycA" class="cyc_term">zAxisPredicateOfSystem</a>. yAxisPredicateOfSystem