Maneuverability is a being's ability to move within a fluid material. This applies to flying in an atmosphere or swimming in a liquid. It is different from agility in that agility implies that the being is stuck to a surface due to gravity.
The maneuverability value has two main uses in game play. It may add a bonus or negative to duck and it is added to all movement rolls (i.e.: speed + maneuverability + movement roll)
These rules only apply if the being is using his maneuverability. For example, an Opteryx who isn't flying will not get any maneuverability bonuses. The absolute range for maneuverability is -10 to 10, but each species has a specific range its members can be.
For beings whose primary locomotion varies between moving though a fluid using maneuverability, or traveling along a surface using agility (e.g.: Frudzug), the bonus to duck they earn through occupations cannot be for both situations. They must split their bonus to duck between surface movement situations and flying/swimming situations. Also, the bonus to duck obtained from agility does not apply when using maneuverability, and vice-versa.