Name	Data Type	Definition
type	CodeObstacleAssessmentSurfaceType	Indicated the type of area being assessed such as 40:1, 72:1, MA, Final, etc
sectionNumber	NoNumberType	a sequence number indicating a part of an assessment area.
slope	ValSlopeType	The slope value of the extent
assessedAltitude	ValDistanceVerticalType	Highest of the minimum altitudes in controlling obstacles plus the altitude adjustments (operational factors)
slopeLowerAltitude	ValDistanceVerticalType	The altitude at the bottom of the assessment area
gradientLowHigh	ValSlopeType	Low to high gradient within the airspace
surfaceZone	CodeObstructionIdSurfaceZoneType	Specifies zones within obstruction identification surfaces (OIS)
safetyRegulation	TextNameType	Identifier for the safety regulations in effect within the zone

Association	Multiplicity	Role	To	Role description
startsWith	0..1	startingCurve	Curve	The curve that starts the ObstacleAssessmentArea.
hasExtent	0..1	surface	Surface	The geographical representation of the Assessment Area.
hasAnnotations	0..*	annotation	Note
isEvaluatedFor	0..*	aircraftCategory	AircraftCharacteristic	Classification of aircraft based on 1.3 times stall speed in landing configuration at maximum certified landing mass.
isResolvedBy	0..*	significantObstacle	Obstruction	The obstacle that controls the altitude definition of the assessment area would penetrate the 40:1 OCS

From	Association	Multiplicity	Role	To	Role description
ApproachCondition	isEvaluatedBy	0..*	designSurface	An evaluation area used when designing a procedure to insure safety of aircraft
CirclingArea	isEvaluatedBy	0..*	designSurface	An evaluation area used when designing circling to insure safety of aircraft
NavigationAreaRestriction	isEvaluatedBy	0..1	designSurface	An evaluation area used when designing a procedure to insure safety of aircraft
SegmentLeg	isEvaluatedBy	0..*	designSurface	An evaluation area used when designing a procedure segment to insure safety of aircraft
RouteSegment	isEvaluatedWith	0..1	evaluationArea	The obstacle evaluation area for the route segment.
HoldingAssessment	isEvaluateBy	0..*	obstacleAssessment	ObstacleAssessmentArea used in a HoldingAssessment.

1 - Circling , 1 - Final Segment Leg Conditions , 1 - Obstacle Assessment Feature , 2 - Obstacle Assessment Associations , 2 - Restricted Navigation , 2 - Route Segment , 2 - Unplanned Holding