######## Glossary ######## .. glossary:: Augmented Reality AR An enhanced version of reality created by the use of technology to overlay digital information on an image of something being viewed through a device. See `Augmented Reality `__. Base The equator of the :term:`flight hemisphere`. This lies at a height of 1.5 m above the center of the :term:`flight circle`. Field of view FOV The area visible through the lens of an optical instrument. Figure A shape, which makes up a separately recognizable complete part of a whole :term:`maneuver`. For example, the first loop of the three consecutive inside loops maneuver is referred to as a figure; but the first loop which makes the first half of the first complete figure eight in the two consecutive overhead eight maneuver is not referred to as a figure. Flight circle A horizontal circle whose radius is equal to the :term:`flight radius`. Flight hemisphere A half-globe shape whose base is level above the ground. Flight radius The distance from the pilot's chest to the centerline of the model aircraft. Great circle The circular intersection of a :term:`sphere` and a plane passing through the sphere's center point. See `Great circle `__. Horizontal Flight along or parallel to the :term:`base`. Inverted Condition when the model aircraft is flying in an attitude which is the reverse of :term:`upright` flight (colloquially, the model aircraft is "flying on its back", is "flying upside-down", or is "flying inverted"). Lateral reference An imaginary line drawn at right angles (90 degrees) to the :term:`horizontal` and is used as a reference line when flying and scoring the size, positioning, symmetry and the superimposition of various :term:`figures
` and :term:`maneuvers `. Level At right angles to the direction aligned with the direction of the force of gravity, as materialized with a plumb line. Manoeuvre Maneuver The full total of :term:`figures
` and :term:`segments ` necessary to complete the maneuver marked under a separate numbered heading with bold type. For example, the take-off maneuver, the three consecutive inside loops maneuver, and the single four-leaf clover maneuver, are all referred to as a single whole maneuver throughout F2B Rules. Markers Physical items in the field arranged according to the recommendation in **Annex 4F, Appendix II** of the `FAI Sporting Code `__. Markers enable production of :term:`Augmented Reality` videos. Momentary Momentarily Used throughout F2B Rules in their original dictionary definition sense (that is: something that lasts only for a very brief period of time). So, for example, the very short period during which the model aircraft is required to be in a vertically-banked "knife-edge" attitude above the competitor's head during the two consecutive overhead eights maneuver is described in F2B Rules as "momentarily". Nominal A dimension, shape, or size that represents the true profile of a :term:`figure` or :term:`maneuver`, and is used as the template against which actual shapes and sizes of figures or maneuvers are compared. Parallel An imaginary line on the surface of the :term:`flight hemisphere` equidistant to the equator of the flight hemisphere and marking the latitude. Segment A specifically defined part of a :term:`figure` (or of a whole :term:`maneuver`) in which certain particular points are detailed. For example, the first loop which makes the first half of the first complete figure eight in the two consecutive overhead eight maneuver is referred to as a segment. Small arc Any arc of a :term:`small circle`. Small circle The circular intersection of a :term:`sphere` and a plane that does not pass through the sphere's center point. See `Small circle `__. Sphere A three-dimensional surface, all points of which are equidistant from a fixed point. Straight line A :term:`great circle` path or part thereof. Top of circle A point at the top of the :term:`flight hemisphere`, vertically above the center of the hemisphere. Upright Condition when the model aircraft is flying in its "normal" upright attitude (that is: with its landing gear nearest to the ground). Vertical Flight at right angles to the :term:`base`, along an imaginary circle on the surface of the :term:`flight hemisphere` marking the longitude. Wingover path The :term:`vertical` climbing and diving flight path defined as a :term:`segment` of the single reverse wingover :term:`maneuver`.