XrViewStateFlagBits(3) Manual Page

XR_VIEW_STATE_ORIENTATION_VALID_BIT indicates whether all XrView orientations contain valid data. Applications must not read any of the XrView pose orientation fields if this flag is unset. XR_VIEW_STATE_ORIENTATION_TRACKED_BIT should generally remain set when this bit is set for views on a tracked headset or handheld device.

XR_VIEW_STATE_POSITION_VALID_BIT indicates whether all XrView positions contain valid data. Applications must not read any of the XrView::pose position fields if this flag is unset. When a view loses tracking, runtimes should continue to provide valid but untracked view position values that are inferred or last-known, so long as it’s still meaningful for the application to render content using that position, clearing XR_VIEW_STATE_POSITION_TRACKED_BIT until tracking is recovered.

XR_VIEW_STATE_ORIENTATION_TRACKED_BIT indicates whether all XrView orientations represent an actively tracked orientation. This bit should generally remain set when XR_VIEW_STATE_ORIENTATION_VALID_BIT is set for views on a tracked headset or handheld device.

XR_VIEW_STATE_POSITION_TRACKED_BIT indicates whether all XrView positions represent an actively tracked position. When a view loses tracking, runtimes should continue to provide valid but untracked view position values that are inferred or last-known, e.g. based on neck model updates, inertial dead reckoning, or a last-known position, so long as it’s still meaningful for the application to render content using that position.