This is a specialization of the GM_Surface class and it inherits all attributes and associations of that class.

Name	Data Type	Definition
horizontalAccuracy	ValDistanceType	The difference between the recorded horizontal coordinates of a feature and its true position referenced to the same geodetic datum expressed as a circular error at 95 percent probability.

Association	Multiplicity	Role	To	Role description
hasAnnotations	0..*	annotation	Note

From	Association	Multiplicity	Role	To	Role description
AirspaceVolume	hasBoundary	0..1	horizontalProjection	The surface defining the horizontal shape of the AirspaceVolume.
ObstacleAssessmentArea	hasExtent	0..1	surface	The geographical representation of the Assessment Area.
RadioFrequencyArea	isDefinedBy	0..*	extent	The graphical area described for the RadioFrequencyArea.
PointReference	hasFixError	0..1	fixToleranceArea	The dimensions of the fix tolerance area are determined by the system use accuracy of the navigation aid(s) on which the fix is based, and the distance from the facility.
ObstacleArea	hasExtent	0..1	surfaceExtent	Extent of the obstacle area.
CirclingArea	isIllustratedBy	0..1	extent	The geographic depiction of the circling area
CirclingRestriction	isDepictedBy	0..1	restrictionArea	The geographical depiction of the Circling restriction.
TerminalArrivalArea	projects	0..1	buffer	The graphical area describing the buffer defined around a Terminal Arrival Area.
TerminalArrivalAreaSector	shows	0..1	extent	The graphical area described for the Terminal Arrival sector.
NavigationAreaSector	isPortrayedBy	0..1	extent	The surface extent of the navigation area sector.
SafeAltitudeAreaSector	isPortrayedBy	0..1	extent	The graphical area described for the Safe Area sector.
AerialRefuellingAnchor	hasExtent	0..1	extent	The Surface extent of the AerialRefuellingAnchor.

This class is specialized into: ElevatedSurface

1 - Aerial Refuelling , 1 - Airspace Feature , 1 - Circling , 1 - Geometry , 1 - Minimum and Emergency Safe Altitude , 1 - Obstacle Assessment Feature , 1 - Segment Points , 1 - Terminal Arrival Area , 1- Radio Frequency Limitation , 2 - Communication Channel , 2 - NavigationArea , 2 - Point Reference , 2 - RestrictedNavigationArea , 3 - Navaid Limitation , 3 - Obstacle Areas