The wing window (riders also say wind window, the kite term it comes from) is the arc of sky downwind of the rider where a parawing can fly. Where the canopy sits in that arc determines the pull: deep in the window means maximum power and downwind drag, out toward the window's edge means less pull and more upwind drive. Canopy construction sets the default position: single-skins sit deep, double-skins fly further forward.
Think of the quarter-sphere downwind of you where the canopy holds pressure. Low on either side, maximum power directly downwind, minimal pull out at the forward edge. That arc is the window, and since a parawing cannot fly upwind of you, power management comes down to where in the window the canopy sits.
A single-skin sits deeper: fast to deploy, strong pull, limited upwind drive. Sheet it out and it drags you downwind anyway. Double-skin and ram-air designs fly further toward the edge; per BRM’s own site, “double skins… continue to drive upwind even when completely sheeted out to the lowest possible angle of attack.” Ozone’s own ratings show the spread: the deep-flying stash-and-glide PowerPack scores roughly 7/10 upwind against the Pocket Rocket’s 9–10/10.
On takeoff, point the board roughly 45° between crosswind and dead downwind. Straight downwind kills apparent wind and line tension, and the wing falls deep into the window with nothing to pull against. In marginal wind, MACkite’s S-Start method has you point 10–15° off dead downwind and use a bump’s backside for the slingshot. To depower, sheet onto the front/A-lines rather than letting the wing wander deep.
Flysurfer’s free Parawing (POW) Academy covers the window in its first episode alongside the bridle system. For applied window control, see riding upwind and water start and takeoff. All terms: glossary.